The PCIe device
FireWire (IEEE 1394) [0c00]: Ricoh Co Ltd FireWire Host Controller
[1180:e832] (prog-if 10 [OHCI])
is unable to access attached FireWire devices when MSI is enabled but
works if MSI is disabled.
http://www.mail-archive.com/alsa-user@lists.sourceforge.net/msg28251.html
Hence add the "disable MSI" quirks flag for this device, or in fact for
safety and simplicity for all current (R5U230, R5U231, R5U240) and
future Ricoh PCIe 1394 controllers.
Reported-by: Stefan Thomas <kontrapunktstefan@googlemail.com>
Cc: 2.6.36+ <stable@vger.kernel.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The Audigy's SB1394 controller is actually from Texas Instruments
and has the same bus reset packet generation bug, so it needs the
same quirk entry.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: 2.6.36+ <stable@vger.kernel.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Add the dma_sync_single_* calls necessary to ensure proper cache
synchronization for isochronous data buffers on non-coherent
architectures.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
If a device's firmware initiates a bus reset by setting the IBR bit in
PHY register 1 without resetting the gap count field to 63 (and without
having sent a PHY configuration packet beforehand), the gap count of
this node will remain at the old value after the bus reset and thus be
inconsistent with the gap count on all other nodes.
The bus manager is supposed to detect the inconsistent gap count values
in the self ID packets and correct them by issuing another bus reset.
However, if the buggy device happens to be the cycle master, and if it
sends a cycle start packet immediately after the bus reset (which is
likely after a long bus reset), then the time between the end of the
selfID phase and the start of the cycle start packet will be based on
the too-small gap count value, so this gap will be too short to be
detected as a subaction gap by the other nodes. This means that the
cycle start packet will be assumed to be self ID data, and will be
stored after the actual self ID quadlets in the self ID buffer.
This garbage in the self ID buffer made firewire-core ignore all of the
self ID data, and thus prevented the Linux bus manager from correcting
the problem. Furthermore, because the bus reset handling was aborted
completely, asynchronous transfers would be no longer handled correctly,
and fw_run_transaction() would hang until the next bus reset.
To fix this, make the detection of inconsistent self IDs more
discriminating: If the invalid data in the self ID buffer looks like
a cycle start packet, we can assume that the previous data in the buffer
is correctly received self ID information, and process it normally.
(We inspect only the first quadlet of the cycle start packet, because
this value is different enough from any valid self ID quadlet, and many
controllers do not store the cycle start packet in five quadlets because
they expect self ID data to have an even number of quadlets.)
This bug has been observed when a bus-powered DesktopKonnekt6 is
switched off with its power button.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Change memory region to ohci "middle address space". This effectively
reduces the number of packets by 50%.
[Stefan R.:] This eliminates 1394 ack packets and improved throughput
by a few percent in some tests with an S400a connection with and without
gap count optimization. Since firewire-net taxes the AR-req DMA unit of
a FireWire controller much more than firewire-sbp2 (which uses the
middle address space with PCI posted writes too), this commit also
changes a related error printk into a ratelimited one as a precaution.
Side note: The IPv4-over-1394 drivers of Mac OS X 10.4, Windows XP SP3,
and the Thesycon 1394 bus driver for Windows all use the middle address
space too.
Signed-off-by: Stephan Gatzka <stephan@gatzka.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Takes less source code and machine code, and less runtime with PHYs
other than TSB41BA3D (e.g. TSB81BA3 with device ID 0x831304 which takes
one instead of six read_paged_phy_reg now).
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Fix: phy_reg_mutex must be held over the write/read_phy_reg pair which
gets PHY port status.
Only print to the log when a TSB41BA3D was found. By far most TSB82AA2
cards have a TSB81BA3, and firewire-ohci can keep quiet about that.
Shorten some strings and comments. Change some whitespace.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This patch implements a work around for the Texas Instruments PHY
TSB41BA3D. This phy has a bug at least in combination with the TI LLCs
TSB82AA2B and TSB12LV26. The selfid coming from the locally connected
phy is not propagated into the selfid buffer of the OHCI (see
http://www.ti.com/litv/pdf/sllz059 for details). The main idea is to
construct the selfid ourselves.
Signed-off-by: Stephan Gatzka <stephan@gatzka.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Code inside bus_reset_work may now sleep. This is a prerequisite to
support a phy from Texas Instruments cleanly. The patch to support this
phy will be submitted later.
Signed-off-by: Stephan Gatzka <stephan@gatzka.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This fixes https://bugs.launchpad.net/ubuntu/+source/linux/+bug/801719 .
An O2Micro PCI Express FireWire controller,
"FireWire (IEEE 1394) [0c00]: O2 Micro, Inc. Device [1217:11f7] (rev 05)"
which is a combination device together with an SDHCI controller and some
sort of storage controller, misses SBP-2 status writes from an attached
FireWire HDD. This problem goes away if MSI is disabled for this
FireWire controller.
The device reportedly does not require QUIRK_CYCLE_TIMER.
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (amended changelog)
Cc: <stable@kernel.org>
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
firewire: ohci: fix DMA unmapping in an error path
firewire: cdev: fix 32 bit userland on 64 bit kernel compat corner cases
If request_irq failed, we would pass wrong arguments to
dma_free_coherent. https://bugzilla.redhat.com/show_bug.cgi?id=728185
Reported-by: Mads Kiilerich
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
When firewire-ohci is bound to a Pinnacle MovieBoard, eventually a
"Register access failure" is logged and an interrupt storm or a kernel
panic happens. https://bugzilla.kernel.org/show_bug.cgi?id=36622
Until this is sorted out (if that is going to succeed at all), let's
just prevent firewire-ohci from touching these devices.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: <stable@kernel.org>
The software reset in firewire-ohci's pci_remove does not have a great
prospect of success if the card was already physically removed at this
point. So let's skip the 500 ms that were spent in retries here.
Also, replace a defined constant by its open-coded value. This is not a
constant from a specification but an arbitrarily chosen retry limit. It
was only used in this single place.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Detect and handle ejection of FireWire CardBus cards in PHY register
accesses:
- The last attempt of firewire-core to reset the bus during shutdown
caused a spurious "firewire_ohci: failed to write phy reg" error
message in the log. Skip this message as well as the prior retry
loop that needlessly took 100 milliseconds.
- In the unlikely case that a PHY register was read right after card
ejection, a bogus value was obtained and possibly acted upon.
Instead, fail the read attempt.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Stopping an isochronous reception DMA context takes two loop iterations
in context_stop on several controllers (JMicron, NEC, VIA). But there
is no extra delay necessary between these two reg_read trials; the MMIO
reads themselves are slow enough. Hence bring back the behavior from
before commit dd6254e5c0 "firewire: ohci:
remove superfluous posted write flushes" on these controllers by means
of an "if (i)" condition.
Isochronous context stop is performed in preemptible contexts (and only
rarely), hence this change is of little impact. (Besides, Agere and TI
controllers always, or almost always, have the context stopped already
at the first ContextControl read.)
More important is asynchronous transmit context stop, which is performed
while local interrupts are disabled (on the two AT DMAs in
bus_reset_tasklet, i.e. after a self-ID-complete event). In my
experience with several controllers, tested with a usermode AT-request
transmitter as well as with FTP transmission over firewire-net, the AT
contexts were luckily already stopped at the first ContextControl read,
i.e. never required another MMIO read let alone mdelay. A possible
explanation for this is that the controllers which I tested perhaps stop
AT DMA before they perform the self-ID reception DMA.
But we cannot be sure about that and should keep the interrupts-disabled
busy loop as short as possible. Hence, query the ContextControl
register in 1000 udelay(10) intervals instead of 10 udelay(1000)
intervals. I understand from an estimation by Clemens Ladisch that
stopping a busy DMA context should take microseconds or at worst tens of
microseconds, not milliseconds.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The call to flush_writes() in context_stop() is superfluous because
another register read is done immediately afterwards.
The call to flush_writes() in ar_context_run() does not need to be done
individually for each AR context, so move it to ohci_enable(). This
also makes ohci_enable() clearer because it no longer depends on a side
effect of ar_context_run() to flush its own register writes.
Finally, the setting of a context's wake bit does not need to be flushed
because neither the driver logic nor the API require the CPU to wait for
this action. This removes the last MMIO reads from the packet queueing
code paths.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
When queueing iso packets, the run time is dominated by the two
MMIO accesses that set the DMA context's wake bit. Because most
drivers submit packets in batches, we can save much time by
removing all but the last wakeup.
The internal kernel API is changed to require a call to
fw_iso_context_queue_flush() after a batch of queued packets.
The user space API does not change, so one call to
FW_CDEV_IOC_QUEUE_ISO must specify multiple packets to take
advantage of this optimization.
In my measurements, this patch reduces the time needed to queue
fifty skip packets from userspace to one sixth on a 2.5 GHz CPU,
or to one third at 800 MHz.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Current implementation of ohci_set_config_rom() uses a deferred
bus reset via fw_schedule_bus_reset(). If clients add multiple
unit descriptors to the config_rom in quick succession, the
deferred bus reset may not have fired before succeeding update
requests have come in. This can lead to an incorrect partial
update of the config_rom for both addition and removal of
config_rom descriptors, as the ohci_set_config_rom() routine
will return -EBUSY if a previous pending update has not been
completed yet; the requested update just gets dropped on the floor.
This patch recognizes that the "in-flight" update can be modified
until it has been processed by the bus-reset, and the locking
in the bus_reset_tasklet ensures that the update is done atomically
with respect to modifications made by ohci_set_config_rom(). The
-EBUSY error case is simply removed.
[Stefan R: The bug always existed at least theoretically. But it
became easy to trigger since 2.6.36 commit 02d37bed18 "firewire: core:
integrate software-forced bus resets with bus management" which
introduced long mandatory delays between janitorial bus resets.]
Signed-off-by: Benjamin Buchalter <bj@mhlabs.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (trivial style changes)
Cc: <stable@kernel.org> # 2.6.36.y and newer
When z==2, the condition "key == 2" is superfluous because it cannot
occur without "b == 3", as a descriptor with b!=3 and key==2 would be
an OUTPUT_MORE_IMMEDIATE descriptor which cannot be used alone.
Also remove magic numbers and needless computations on the b field.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
For AT packet payloads of up to eight bytes, we have enough unused space
in the DMA descriptors list so that we can put a copy of the payload
there and thus avoid having to create a separate streaming DMA mapping
for the payload buffer.
In a CPU-bound microbenchmark that just sends 8-byte packets, bandwidth
was measured to increase by 5.7 %, from 1009 KB/s to 1067 KB/s. In
practice, the only performance-sensitive usage of small asynchronous
packets is the SBP-2 driver's write to the ORB_POINTER register during
SCSI command submission.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
OHCI 1.1 5.7.3 not only forbids enabling or starting any DMA contexts
before the linkEnable bit is set, but also explicitly warns of undefined
behaviour if this order is violated.
Don't violate it then.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
It seems drivers/firewire/ohci.c is making some optimistic assumptions
about struct fw_ohci and that member "card" will always remain the first
member of the struct.
Plus it's probably going to confuse a lot of static code analyzers too.
So I wonder if there is a good reason not to free the ohci struct just
like it was allocated instead of the tricky &ohci->card way?
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
It is perhaps just a rudiment from before mainline submission of the
driver.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Since commit 82b662dc41 "flush AT contexts after bus reset for OHCI 1.2",
the driver takes care of any AT packets that were enqueued during a bus
reset phase. The check from commit 76f73ca1b2 is therefore no longer
necessary and the MMIO read can be avoided.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
If a misguided program tried to start an isochronous context before it
has queued any packets, the call would appear to succeed, but the
context would not actually go into the running state, and the OHCI
controller would then raise an unrecoverableError interrupt because the
first Z value is zero and thus invalid. The driver logs such errors,
but there is no mechanism to report this back to the program.
Add an explicit check so that this error can be returned synchronously.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
To prevent the iso packet callback from being called after
fw_iso_context_stop() has returned, make sure that the
context's tasklet has finished executing before that.
This fixes access-after-free bugs that have so far been
observed only in the upcoming snd-firewire-speakers driver,
but can theoretically also happen in the firedtv driver.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
When a DMA context goes into the dead state (and the controller thus
stops working correctly), logging this error and the controller's error
code might be helpful for debugging.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
PAGE_KERNEL_RO is not available on all architectures, so its use
in the new AR code broke compilation on sparc64.
Because the read-only mapping was just a debugging aid, just use
PAGE_KERNEL instead.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
James Bottomley wrote:
> On Thu, 2011-01-13 at 08:27 +0100, Clemens Ladisch wrote:
>> firewire: ohci: fix compilation on arches without PAGE_KERNEL_RO, e.g. sparc
>>
>> PAGE_KERNEL_RO is not available on all architectures, so its use in the
>> new AR code broke compilation on sparc64.
>>
>> Because the R/O mapping is only used to catch drivers that try to write
>> to the reception buffer and not actually required for correct operation,
>> we can just use a normal PAGE_KERNEL mapping where _RO is not available.
[...]
>> +/*
>> + * For archs where PAGE_KERNEL_RO is not supported;
>> + * mapping the AR buffers readonly for the CPU is just a debugging aid.
>> + */
>> +#ifndef PAGE_KERNEL_RO
>> +#define PAGE_KERNEL_RO PAGE_KERNEL
>> +#endif
>
> This might cause interesting issues on sparc64 if it ever acquired a
> PAGE_KERNEL_RO. Sparc64 has extern pgprot_t for it's PAGE_KERNEL types
> rather than #defines, so the #ifdef check wouldn't see this.
>
> I think either PAGE_PROT_RO becomes part of our arch API (so all
> architectures are forced to add it), or, if it's not part of the API,
> ohci isn't entitled to use it. The latter seems simplest since you have
> no real use for write protection anyway.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
"firewire: ohci: restart iso DMA contexts on resume from low power mode"
added the flag struct context.active and "firewire: ohci: cache the
context run bit" added struct context.running.
These flags contain the same information; combine them.
Also, normalize whitespace in pci_resume().
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The DMA context run control bit is entirely controlled by software, so
it is safe to cache it. This allows the driver to avoid doing an
additional MMIO read when queueing an AT packet.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Add comments
- on why bus_reset_tasklet flushes AT queues,
- that commit 76f73ca1b2 can possibly be reverted now.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Jarod Wilson <jarod@redhat.com>
The OHCI 1.2 (draft) specification, clause 7.2.3.3, allows and
recommends that, after a bus reset, the controller does not flush all
the packets in the AT queues. Therefore, the driver has to do this
itself.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Restore iso channels DMA so that iso channels could continue to work
after resume from RAM/disk.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Some lousy BIOSes, e.g. my Aspire 5720 BIOS forget to restore the GUID
register on resume from RAM.
Fix that by setting it to the last value that was read from it.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The buffers used for the selfIDs packets and the AR request and response
descriptors end up using three pages because dma_alloc_coherent()
allocates at least one page per call. However, these data structures
would all fit into 4 KB, so we can save space by using a common buffer
for them.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
When the isochRx/isochTx bit is clear, we do not need to read the
corresponding iso interrupt event register.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Change the header of PHY packets to be sent to include a pseudo
transaction code. This makes the header consistent with that of
received PHY packets, and allows at_context_queue_packet() and
log_ar_at_event() to see the packet type directly instead of having
to deduce it from the header length or even from the header contents.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
To remove the error information from the controller's queue and to allow
more posted writes, the driver has to read the failed posted write
address before clearing the postedWriteErr interrupt bit.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
(Stefan R:) The spec is somewhat fuzzy about the actual requirements.
To err on the safe side, let's do these two read accesses.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Make sure that interrupt event clear bit writes are executed before the
interrupt handler returns.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Add proper error handling for the context_init() calls.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Move the AR DMA descriptors out of the buffer pages, and map the buffer
pages linearly into the kernel's address space. This allows the driver
to ignore any page boundaries in the DMA data and thus to avoid any
copying around of packet payloads.
This fixes the bug where S800 packets that are so big (> 4080 bytes)
that they can be split over three pages were not handled correctly.
Due to the changed algorithm, we can now use arbitrarily many buffer
pages, which improves performance because the controller can more easily
unload its DMA FIFO.
Furthermore, using streaming DMA mappings should improve perfomance on
architectures where coherent DMA mappings are not cacheable. Even on
other architectures, the caching behaviour should be improved slightly
because the CPU no longer writes to the buffer pages.
v2: Detect the last filled buffer page by searching the descriptor's
residual count value fields in order (like in the old code), instead
of going backwards through the transfer status fields; it looks as
if some controllers do not set the latter correctly.
v3: Fix an old resume bug that would now make the handler run into
a BUG_ON, and replace that check with more useful error handling.
Increase the buffer size for better performance with non-TI chips.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Maxim Levitsky writes:
Works almost perfectly. I can still see RCODE_BUSY errors
sometimes, not very often though. 64K here eliminates these errors
completely. This is most likely due to nouveau drivers and lowest
perf level I use to lower card temperature. That increases
latencies too much I think. Besides that the IO is just perfect.
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Agere FW643 rev 06, listed as "11c1:5901 (rev 06) (prog-if 10 [OHCI])",
produced SBP-2 I/O errors since kernel 2.6.36. Disabling MSI fixes it.
Since MSI work on Agere FW643-E (same vendor and device ID, but rev 07),
introduce a device revision field into firewire-ohci's quirks list so
that different quirks can be defined for older and newer revisions.
Reported-by: Jonathan Isom <jeisom@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: <stable@kernel.org> # 2.6.36.y
"VIA Technologies, Inc. VT6315 Series Firewire Controller [1106:3403]"
does not generate any interrupts if Message Signaled Interrupts were
enabled. This is a regression since kernel 2.6.36 in which MSI support
was added to firewire-ohci. Hence blacklist MSI on all VIA controllers.
Reported-by: Robin Cook <rcook@wyrms.net>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: <stable@kernel.org> # 2.6.36.y
If the controller is storing a split packet and therefore changing
d->res_count to zero between the two reads by the driver, we end up with
an end pointer that is not at a packet boundary, and therefore overflow
the buffer when handling the split packet.
To fix this, read the field once, atomically. The compiler usually
merges the two reads anyway, but for correctness, we have to enforce it.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Freeing an AR buffer page just to allocate a new page immediately
afterwards is not only a pointless effort but also dangerous because
the allocation can fail, which would result in an oops later.
Split ar_context_add_page() into two functions so that we can reuse
the old page directly.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
When handling an AR buffer that has been completely filled, we assumed
that its descriptor will not be read by the controller and can be
overwritten. However, when the last received packet happens to end at
the end of the buffer, the controller might not yet have moved on to the
next buffer and might read the branch address later. If we overwrite
and free the page before that, the DMA context will either go dead
because of an invalid Z value, or go off into some random memory.
To fix this, ensure that the descriptor does not get overwritten by
using only the actual buffer instead of the entire page for reassembling
the split packet. Furthermore, to avoid freeing the page too early,
move on to the next buffer only when some data in it guarantees that the
controller has moved on.
This should eliminate the remaining firewire-net problems.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: 2.6.22-2.6.36 <stable@kernel.org>
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
When the controller had to split a received asynchronous packet into two
buffers, the driver tries to reassemble it by copying both parts into
the first page. However, if size + rest > PAGE_SIZE, i.e., if the yet
unhandled packets before the split packet, the split packet itself, and
any received packets after the split packet are together larger than one
page, then the memory after the first page would get overwritten.
To fix this, do not try to copy the data of all unhandled packets at
once, but copy the possibly needed data every time when handling
a packet.
This gets rid of most of the infamous crashes and data corruptions when
using firewire-net.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: 2.6.22-2.6.36 <stable@kernel.org>
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (cast PAGE_SIZE to size_t)
Revert commit 54672386cc
"firewire: ohci: fix up configuration of TI chips".
It caused massive slow-down and data corruption with a TSB82AA2 based
StarTech EC1394B2 ExpressCard and FireWire 800 harddisks.
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/657081http://thread.gmane.org/gmane.linux.kernel.firewire.user/4013
The fact that some card EEPROMs do not program these enhancements may be
related to TSB81BA3 phy chip errata, if not to bugs of TSB82AA2 itself.
We could re-add these configuration steps, but only conditional on a
whitelist of cards on which these enhancements bring a proven positive
effect.
Reported-and-tested-by: Eric Shattow <lucent@gmail.com>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org> 2.6.35
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The Ricoh FireWire controllers appear to have the non-atomic cycle
timer register access bug, so, activate the driver workaround by
default.
The behaviour was observed on:
Ricoh Co Ltd R5C552 IEEE 1394 Controller [1180:0552] and
Ricoh Co Ltd R5C832 IEEE 1394 Controller [1180:0832] (rev 04).
Signed-off-by: Heikki Lindholm <holin@iki.fi>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
VIA VT6306, VIA VT6308, and NEC OrangeLink controllers do not write
packet event codes for received PHY packets (or perhaps write
evt_no_status, hard to tell). Work around it by overwriting the
packet's ACK by ack_complete, so that upper layers that listen to PHY
packet reception get to see these packets.
(Also tested: TI TSB82AA2, TI TSB43AB22/A, TI XIO2213A, Agere FW643,
JMicron JMB381 --- these do not exhibit this bug.)
Clemens proposed a quirks flag for that, IOW whitelist known misbehaving
controllers for this workaround. Though to me it seems harmless enough
to enable for all controllers.
The log_ar_at_event() debug log will continue to show the original
status from the DMA unit.
Reported-by: Clemens Ladisch <clemens@ladisch.de> (VT6308)
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Conflicts:
drivers/firewire/core-card.c
drivers/firewire/core-cdev.c
and forgotten #include <linux/time.h> in drivers/firewire/ohci.c
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This adds the DMA context programming and userspace ABI for multichannel
reception, i.e. for listening on multiple channel numbers by means of a
single DMA context.
The use case is reception of more streams than there are IR DMA units
offered by the link layer. This is already implemented by the older
ohci1394 + ieee1394 + raw1394 stack. And as discussed recently on
linux1394-devel, this feature is occasionally used in practice.
The big drawbacks of this mode are that buffer layout and interrupt
generation necessarily differ from single-channel reception: Headers
and trailers are not stripped from packets, packets are not aligned with
buffer chunks, interrupts are per buffer chunk, not per packet.
These drawbacks also cause a rather hefty code footprint to support this
rarely used OHCI-1394 feature. (367 lines added, among them 94 lines of
added userspace ABI documentation.)
This implementation enforces that a multichannel reception context may
only listen to channels to which no single-channel context on the same
link layer is presently listening to. OHCI-1394 would allow to overlay
single-channel contexts by the multi-channel context, but this would be
a departure from the present first-come-first-served policy of IR
context creation.
The implementation is heavily based on an earlier one by Jay Fenlason.
Thanks Jay.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
firewire-ohci keeps book of which isochronous channels are occupied by
IR DMA contexts, so that there cannot be more than one context listening
to a certain channel.
If IR context creation failed due to an out-of-memory condition, this
bookkeeping leaked a channel.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
When we append to a DMA program, we need to ensure that the order in
which initialization of the new descriptors and update of the
branch_address of the old tail descriptor, as seen by the PCI device,
happen as intended.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This extends the FW_CDEV_IOC_SEND_PHY_PACKET ioctl() for /dev/fw* to be
useful for ping time measurements. One application for it would be gap
count optimization in userspace that is based on ping times rather than
hop count. (The latter is implemented in firewire-core itself but is
not applicable to beta PHYs that act as repeater.)
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Add an FW_CDEV_IOC_RECEIVE_PHY_PACKETS ioctl() and
FW_CDEV_EVENT_PHY_PACKET_RECEIVED poll()/read() event for /dev/fw*.
This can be used to get information from remote PHYs by remote access
PHY packets.
This is also the 2nd half of the functionality (the receive part) to
support a userspace implementation of a VersaPHY transaction layer.
Safety considerations:
- PHY packets are generally broadcasts, hence some kind of elevated
privileges should be required of a process to be able to listen in
on PHY packets. This implementation assumes that a process that is
allowed to open the /dev/fw* of a local node does have this
privilege.
There was an inconclusive discussion about introducing POSIX
capabilities as a means to check for user privileges for these
kinds of operations.
Other limitations:
- PHY packet reception may be switched on by ioctl() but cannot be
switched off again. It would be trivial to provide an off switch,
but this is not worth the code. The client should simply close()
the fd then, or just ignore further events.
- For sake of simplicity of API and kernel-side implementation, no
filter per packet content is provided.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Bus resets which are triggered
- by the kernel drivers after updates of the local nodes' config ROM,
- by userspace software via ioctl
shall be deferred until after >=2 seconds after the last bus reset.
If multiple modifications of the local nodes' config ROM happen in a row,
only a single bus reset should happen after them.
When the local node's link goes from inactive to active or vice versa,
and at the two occasions of bus resets mentioned above --- and if the
current gap count differs from 63 --- the bus reset should be preceded
by a PHY configuration packet that reaffirms the gap count. Otherwise a
bus manager would have to reset the bus again right after that.
This is necessary to promote bus stability, e.g. leave grace periods for
allocations and reallocations of isochronous channels and bandwidth,
SBP-2 reconnections etc.; see IEEE 1394 clause 8.2.1.
This change implements all of the above by moving bus reset initiation
into a delayed work (except for bus resets which are triggered by the
bus manager workqueue job and are performed there immediately). It
comes with a necessary addition to the card driver methods that allows
to get the current gap count from PHY registers.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Rather than "read a Control and Status Registers (CSR) Architecture
register" I prefer to say "read a Control and Status Register".
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Push the maintenance of STATE_CLEAR/SET.abdicate down into the card
driver. This way, the read/write_csr_reg driver method works uniformly
across all CSR offsets.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
by feature variables in the fw_card struct. The hook appeared to be an
unnecessary abstraction in the card driver interface.
Cleaner would be to pass those feature flags as arguments to
fw_card_initialize() or fw_card_add(), but the FairnessControl register
is in the SCLK domain and may therefore not be accessible while Link
Power Status is off, i.e. before the card->driver->enable call from
fw_card_add().
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Add a comment on which of the conflicting NODE_IDS specifications we
implement. Reduce a comment on rather irrelevant register bits that can
all be looked up in the spec (or from now on in the code history).
Directly include the required indirectly included bug.h.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
On OHCI 1.1 controllers, let the hardware allocate the broadcast channel
automatically. This removes a theoretical race condition directly after
a bus reset where it could be possible to read the channel allocation
register with channel 31 still being unallocated.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Implement the cmstr bit, which is required for cycle master capable
nodes and tested for by the Base 1394 Test Suite.
This bit allows the bus master to disable cycle start packets; there are
bus master implementations that actually do this.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
If supported by the OHCI controller, implement the PRIORITY_BUDGET
register, which is required for nodes that can use asynchronous
priority arbitration.
To allow the core to determine what features the lowlevel device
supports, add a new card driver callback.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Implement the BUS_TIME register, which is required for cycle master
capable nodes and tested for by the Base 1393 Test Suite. Even when
there is not yet bus master initialization support, this register allows
us to work together with other bus masters.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
The specification requires that CYCLE_TIME is writable so that it can be
initialized, so we better implement it.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
The NODE_IDS register, and especially its bus_id field, is quite
useless because 1394.1 requires that the bus_id field always stays
0x3ff. However, the 1394 specification requires this register on all
transaction capable nodes, and the Base 1394 Test Suite tests for it,
so we better implement it.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
To prepare for the following additions of more OHCI-implemented CSR
registers, replace the get_cycle_time driver callback with a generic
CSR register callback.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Most PHY chips, when idle, can complete a register access in the time
needed for two or three PCI read transactions; bigger delays occur only
when data is currently being moved over the link/PHY interface. So if
we busy-wait a few times when waiting for the register access to finish,
it is likely that we can finish without having to sleep.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
This patch adds support for message-signaled interrupts.
Any native PCI-Express OHCI controller should support MSI, but most are
just PCI cores behind a PCI-E/PCI bridge. The only chips that are known
to claim to support MSI are the Lucent/Agere/LSI FW643 and the VIA
VT6315, none of which I have been able to test.
Due to the high level of trust I have in the competence of these and any
future chip makers, I thought it a good idea to add a disable-MSI quirk.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Tested Agere FW643 rev 07 [11c1:5901] and JMicron JMB381 [197b:2380].
Added a quirks list entry for JMB38X since it kept its count of MSI
events consistently at zero.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
On 26 Apr 2010, Clemens Ladisch wrote:
> In theory, none of the interrupts should occur before the link is
> enabled. In practice, I'd rather make sure to not set the master
> interrupt enable bit until we have installed the interrupt handler.
and proposed to move OHCI1394_masterIntEnable out of the present
reg_write() into a new one before the HCControl.linkEnable reg_write().
Why not defer setting /all/ of the bits until right before linkEnable?
Reviewed-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
ieee1394: schedule for removal
firewire: core: use separate timeout for each transaction
firewire: core: Fix tlabel exhaustion problem
firewire: core: make transaction label allocation more robust
firewire: core: clean up config ROM related defined constants
ieee1394: mark char device files as not seekable
firewire: cdev: mark char device files as not seekable
firewire: ohci: cleanups and fix for nonstandard build without debug facility
firewire: ohci: wait for PHY register accesses to complete
firewire: ohci: fix up configuration of TI chips
firewire: ohci: enable 1394a enhancements
firewire: ohci: do not clear PHY interrupt status inadvertently
firewire: ohci: add a function for reading PHY registers
Trivial conflicts in Documentation/feature-removal-schedule.txt
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (44 commits)
vlynq: make whole Kconfig-menu dependant on architecture
add descriptive comment for TIF_MEMDIE task flag declaration.
EEPROM: max6875: Header file cleanup
EEPROM: 93cx6: Header file cleanup
EEPROM: Header file cleanup
agp: use NULL instead of 0 when pointer is needed
rtc-v3020: make bitfield unsigned
PCI: make bitfield unsigned
jbd2: use NULL instead of 0 when pointer is needed
cciss: fix shadows sparse warning
doc: inode uses a mutex instead of a semaphore.
uml: i386: Avoid redefinition of NR_syscalls
fix "seperate" typos in comments
cocbalt_lcdfb: correct sections
doc: Change urls for sparse
Powerpc: wii: Fix typo in comment
i2o: cleanup some exit paths
Documentation/: it's -> its where appropriate
UML: Fix compiler warning due to missing task_struct declaration
UML: add kernel.h include to signal.c
...
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
firewire: ohci: wait for local CSR lock access to finish
firewire: ohci: prevent aliasing of locally handled register addresses
firewire: core: fw_iso_resource_manage: return -EBUSY when out of resources
firewire: core: fix retries calculation in iso manage_channel()
firewire: cdev: fix cut+paste mistake in disclaimer
Add a loop to wait for the controller to finish a locally-initiated CSR
lock operation. Google shows some occurrences of the "swap not done
yet" message which might indicate that some OHCI controllers are not
fast enough to do the lock/swap in the time needed for one PCI access.
This also correctly handles the case where the lock operation did not
finish, instead of silently returning an uninitialized value.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
We must compute the offset from the CSR register base with the
full 48 address bits to prevent matching with addresses whose
lower 32 bits happen to be equal with one of the specially
handled registers.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
1) Clean up two function names: The ohci_ prefix is only used in names
of fw_card_driver hooks. There were two unnecessary exceptions.
2) Replace empty macros by empty inline functions so that call parameter
type checking is available in #ifndef'd builds.
3) CONFIG_FIREWIRE_OHCI_DEBUG is currently a hidden kconfig variable,
hence is not going to be switched off by anybody. Still, it can be
switched off but then compilation will fail in ohci_enable() at the
expression param_debug & OHCI_PARAM_DEBUG_BUSRESETS. Add the necessary
definitions in the nonstandard case.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Rather than having the arbitrary msleep(2) pause, let read_phy_reg()
loop until the link--phy access was finished.
Factor write_phy_reg() out of ohci_update_phy_reg() and of
read_paged_phy_reg() and let it loop too until the link--phy access was
finished.
Like in the older ohci1394 driver, a timeout of 100 milliseconds is
chosen. Unlike the old driver, we sleep instead of busy-wait in each
waiting loop iteration. Instead of a loop, the waiting could probably
also be implemented interrupt driven, but why bother. It would require
up and running interrupt handling before the link was fully configured
and enabled.
Also modify functions a bit: Error return and value return can be
combined in read_phy_reg() since the domain of values is only u8.
Likewise in read_paged_phy_reg().
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
On TI chips (OHCI-Lynx and later), enable link enhancements features
that TI recommends to be used. None of these are required for proper
operation, but they are safe and nice to have.
In theory, these bits should have been set by default, but in practice,
some BIOS/EEPROM writers apparently do not read the datasheet, or get
spooked by names like "unfair".
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The OHCI spec says that, if the programPhyEnable bit is set, the driver
is responsible for configuring the IEEE1394a enhancements within the PHY
and the link consistently. So do this.
Also add a quirk to allow disabling these enhancements; this is needed
for the TSB12LV22 where ack accelerations are buggy (erratum b).
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The interrupt status bits in PHY register 5 are cleared by writing a one
bit. To avoid clearing them unadvertently, do not write them back when
they were read as set, but only when they have been explicitly requested
to be set.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Move the register reading code from ohci_update_phy_reg() into
a function which can be used separately.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Among the many entries in the TSB12LV22 errata list (TI literature
number SLLS312) is the following:
PCI Slave reads of the Cycle Timer register may occasionally get an
incorrect value.
Software may be able to validate value by reading the register
multiple times rapidly and evaluating for a reasonable difference.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de> (untested)
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (added #define)
by the number of available isochronous DMA contexts and active quirks
which is occasionally useful information.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This bug was present in firewire-ohci since day one: The number of
available isochronous receive DMA contexts was mixed up with that of
available isochronous transmit DMA contexts.
This is harmless on a few chips which offer the same number of contexts
in both directions, but most chips nowadays implement only the standard
minimum of 4 IR contexts, but 8 IT contexts. If a user attempted to run
a lot of IR contexts at once, results with more than four were therefore
unpredictable. I suppose the controller would simply refuse to start
DMA of any unimplemented context.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This way, we can advise users of precompiled kernel packages to test
existing quirk fixes on chips which have not been listed yet, without
them having to build a kernel from source.
Note, to use this feature on a machine with more than one controller,
steps like these are necessary:
# lspci | grep 1394
# ls /sys/bus/pci/drivers/firewire_ohci/
# echo -n "0000:03:02.0" > /sys/bus/pci/drivers/firewire_ohci/unbind
# echo 2 > /sys/module/firewire_ohci/parameters/quirks
# echo -n "0000:03:02.0" > /sys/bus/pci/drivers/firewire_ohci/bind
# echo 0 > /sys/module/firewire_ohci/parameters/quirks
The parameter can also be used to switch off quirk flags that were
hardwired into firewire-ohci's quirks table. Simply specify a non-zero
quirks value but without any known flags, e.g. 0x100.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
We don't have a lot of quirks to take into account (especially since
dual-buffer IR is out of the picture), but still, a table-based approach
is more organized than a series of if () clauses.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The config_rom struct members are only accessed during relatively
infrequent self-ID-complete interrupts and only if the local config ROM
was changed, while the ar_, at_, ir_, it_ members are used very
frequently during I/O. Hence move the config_rom members further down.
More importantly, make the huge self_id_buffer member the last one; this
is only accessed in self-ID-complete interrupts.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This code was no longer used since 2.6.33, "firewire: ohci: always use
packet-per-buffer mode for isochronous reception" commit 090699c0. If
anybody needs this code in the future for special purposes, it can be
brought back in. But it must not be re-enabled by default; drivers
(kernelspace or userspace drivers) should only get this mode if they
explicitly request it.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
The current implementation of Bus_Time read access was buggy since it
did not ensure that Bus_Time.second_count_hi and second_count_lo came
from the same 128 seconds period.
Reported-by: Håkan Johansson <f96hajo@chalmers.se>
Instead of a fix, remove Bus_Time register support altogether. The spec
requires all cycle master capable nodes to implement this (all Linux
nodes are cycle master capable) while it also says that it "may" be
initialized by the bus manager or by the IRM standing in for a bus
manager. (Neither Linux' firewire-core nor ieee1394 nodemgr implement
this.)
Since we cannot rely on Bus_Time having been initialized by a bus
manager, it is better to return an error instead of a nonsensical value
on a read request to Bus_Time.
Alternatively, we could fix the Bus_Time read integrity bug _and_
implement (a) cycle master's write support of the register as well as
(b) bus manager's Bus_Time initialization service, i.e. preservation of
the Bus_Time when the cycle master node of a bus changes. However, that
would be quite some code for a feature that is unreliable to begin with
and very likely unused in practice.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
