Old code in the kernel uses 1-byte and 0-byte arrays to indicate the
presence of a "variable length array":
struct something {
int length;
u8 data[1];
};
struct something *instance;
instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
instance->length = size;
memcpy(instance->data, source, size);
There is also 0-byte arrays. Both cases pose confusion for things like
sizeof(), CONFIG_FORTIFY_SOURCE, etc.[1] Instead, the preferred mechanism
to declare variable-length types such as the one above is a flexible array
member[2] which need to be the last member of a structure and empty-sized:
struct something {
int stuff;
u8 data[];
};
Also, by making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertenly introduced[3] to the codebase from now on.
Lastly, make use of the struct_size() helper to safely calculate the
allocation size for instances of struct n_hdlc_buf and avoid any potential
type mistakes[4][5].
[1] https://github.com/KSPP/linux/issues/21
[2] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
[4] https://lore.kernel.org/lkml/60e14fb7-8596-e21c-f4be-546ce39e7bdb@embeddedor.com/
[5] commit 553d66cb1e ("iommu/vt-d: Use struct_size() helper")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200121172138.GA3162@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
According to termbits.h SPARC supports few more baud rates
than currently defined in tty_baudrate.c.
Append supported ones to baud_table[] and baud_bits[].
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200115224124.74684-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Synchronize baud rate tables baud_table and baud_bits with each other
for better readability. This makes clear what is being used for SPARC.
No functional change intended.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200115224124.74684-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The main irq handler function starts by first masking disabled
interrupts in the status register values to ensure to only handle
enabled interrupts. This is important as when the RX path in the
hardware is disabled reading the RX fifo results in an external abort.
This checking must be done under the port lock, otherwise the following
can happen:
CPU1 | CPU2
|
irq triggers as there are chars |
in the RX fifo |
| grab port lock
imx_uart_int finds RRDY enabled |
and calls imx_uart_rxint which |
has to wait for port lock |
| disable RX (e.g. because we're
| using RS485 with !RX_DURING_TX)
|
| release port lock
read from RX fifo with RX |
disabled => exception |
So take the port lock only once in imx_uart_int() instead of in the
functions called from there.
Reported-by: Andre Renaud <arenaud@designa-electronics.com>
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200121071702.20150-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Document the driver private data of the BCM2835 auxiliary UART so that
upcoming commits may add further members with proper kerneldoc.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/aea363c27fd541dba96d2ebfeee4f596c6d34932.1579175223.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On probe the bcm2835aux UART driver misreports the register base address
as 0x0:
ttyS0 at MMIO 0x0 (irq = 53, base_baud = 50000000) is a 16550
That's because the driver remaps the registers itself. Take advantage
of the generic remapping code in serial8250_request_std_resource() to
get a message with the correct address and to simplify the driver.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/7d1a9bdb05090d8e465fd15cd26d6e81538d07f9.1579175223.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The bcm2835aux UART driver stores a struct uart_8250_port in its private
data even though it's only passed once to serial8250_register_8250_port()
(which copies all relevant data) and becomes obsolete afterwards.
Allocate the struct on the stack instead for simplicity and to conserve
memory.
The driver also initializes a spinlock in the struct which is never used.
Drop that as well.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/421d3aed4c34cc8447ac9c26c320961f1b787f11.1579175223.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Unbinding the bcm2835aux UART driver raises the following error if the
maximum number of 8250 UARTs is set to 1 (via the 8250.nr_uarts module
parameter or CONFIG_SERIAL_8250_RUNTIME_UARTS):
(NULL device *): Removing wrong port: a6f80333 != fa20408b
That's because bcm2835aux_serial_probe() retrieves UART line number 1
from the devicetree and stores it in data->uart.port.line, while
serial8250_register_8250_port() instead uses UART line number 0,
which is stored in data->line.
On driver unbind, bcm2835aux_serial_remove() uses data->uart.port.line,
which contains the wrong number. Fix it.
The issue does not occur if the maximum number of 8250 UARTs is >= 2.
Fixes: bdc5f30095 ("serial: bcm2835: add driver for bcm2835-aux-uart")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v4.6+
Cc: Martin Sperl <kernel@martin.sperl.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/912ccf553c5258135c6d7e8f404a101ef320f0f4.1579175223.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It should remove the align-padding before @name.
[yes, there's a "hole" in the structure now, but that's fine, no one
cares. If they do care, the whole thing should be restructured using
pahole to find a better ordering. Removing this field is good as some
drivers have been known to abuse it for other things when they shouldn't
have been doing that. -- gregkh]
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20200114171912.261787-4-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 3e795de763 ("[PATCH] VT binding: Add binding/unbinding support
for the VT console") introduced a code comment claiming that
"do_take_over_console is basically a register followed by unbind".
However the function actually performs a register followed by *bind*.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Antonino A. Daplas <adaplas@gmail.com>
Link: https://lore.kernel.org/r/a500f005ba7013ca8165a6d42f59b2183d56114f.1578574427.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-25-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-24-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-23-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-22-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-21-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-20-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-19-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-18-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-17-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-16-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-15-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-14-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-13-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-12-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-11-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-10-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-9-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-7-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-6-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-5-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset.
Drop it from arch setup code.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-4-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If the arch setup code hasn't initialized conswitchp yet, set it to
dummy_con in con_init. This will allow us to drop the dummy_con
initialization that's done in almost every architecture.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-3-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit [1] consolidated console configuration in
drivers/video/console, DUMMY_CONSOLE has always been enabled, since the
dependency is always satisfied.
There is no point in trying to allow it to be configured out, since
(a) it's tiny, and (b) if VT_CONSOLE is enabled, we must have a working
console driver by the time con_init(vt.c) runs, and only dummycon is
guaranteed to work (vgacon may be configured in, but that doesn't mean
we have a VGA device).
So just remove the fake dependency.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit?id=31d2a7d36d6989c714b792ec00358ada24c039e7
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20191218214506.49252-2-nivedita@alum.mit.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Clang warns:
../drivers/tty/synclink_gt.c:1337:3: warning: misleading indentation;
statement is not part of the previous 'if' [-Wmisleading-indentation]
if (C_CRTSCTS(tty)) {
^
../drivers/tty/synclink_gt.c:1335:2: note: previous statement is here
if (I_IXOFF(tty))
^
../drivers/tty/synclink_gt.c:2563:3: warning: misleading indentation;
statement is not part of the previous 'if' [-Wmisleading-indentation]
if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
^
../drivers/tty/synclink_gt.c:2561:2: note: previous statement is here
if (I_INPCK(info->port.tty))
^
../drivers/tty/synclink_gt.c:3221:3: warning: misleading indentation;
statement is not part of the previous 'else' [-Wmisleading-indentation]
set_signals(info);
^
../drivers/tty/synclink_gt.c:3219:2: note: previous statement is here
else
^
3 warnings generated.
The indentation on these lines is not at all consistent, tabs and spaces
are mixed together. Convert to just using tabs to be consistent with the
Linux kernel coding style and eliminate these warnings from clang.
Link: https://github.com/ClangBuiltLinux/linux/issues/822
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20191218023912.13827-1-natechancellor@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Clang warns:
../drivers/tty/synclinkmp.c:1456:3: warning: misleading indentation;
statement is not part of the previous 'if' [-Wmisleading-indentation]
if (C_CRTSCTS(tty)) {
^
../drivers/tty/synclinkmp.c:1453:2: note: previous statement is here
if (I_IXOFF(tty))
^
../drivers/tty/synclinkmp.c:2473:8: warning: misleading indentation;
statement is not part of the previous 'if' [-Wmisleading-indentation]
info->port.tty->hw_stopped = 0;
^
../drivers/tty/synclinkmp.c:2471:7: note: previous statement is here
if ( debug_level >= DEBUG_LEVEL_ISR )
^
../drivers/tty/synclinkmp.c:2482:8: warning: misleading indentation;
statement is not part of the previous 'if' [-Wmisleading-indentation]
info->port.tty->hw_stopped = 1;
^
../drivers/tty/synclinkmp.c:2480:7: note: previous statement is here
if ( debug_level >= DEBUG_LEVEL_ISR )
^
../drivers/tty/synclinkmp.c:2809:3: warning: misleading indentation;
statement is not part of the previous 'if' [-Wmisleading-indentation]
if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
^
../drivers/tty/synclinkmp.c:2807:2: note: previous statement is here
if (I_INPCK(info->port.tty))
^
../drivers/tty/synclinkmp.c:3246:3: warning: misleading indentation;
statement is not part of the previous 'else' [-Wmisleading-indentation]
set_signals(info);
^
../drivers/tty/synclinkmp.c:3244:2: note: previous statement is here
else
^
5 warnings generated.
The indentation on these lines is not at all consistent, tabs and spaces
are mixed together. Convert to just using tabs to be consistent with the
Linux kernel coding style and eliminate these warnings from clang.
Link: https://github.com/ClangBuiltLinux/linux/issues/823
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20191218024720.3528-1-natechancellor@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tpk_write()/tpk_close() could be interrupted when holding a mutex, then
in timer handler tpk_write() may be called again trying to acquire same
mutex, lead to deadlock.
Google syzbot reported this issue with CONFIG_DEBUG_ATOMIC_SLEEP
enabled:
BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:938
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/1
1 lock held by swapper/1/0:
...
Call Trace:
<IRQ>
dump_stack+0x197/0x210
___might_sleep.cold+0x1fb/0x23e
__might_sleep+0x95/0x190
__mutex_lock+0xc5/0x13c0
mutex_lock_nested+0x16/0x20
tpk_write+0x5d/0x340
resync_tnc+0x1b6/0x320
call_timer_fn+0x1ac/0x780
run_timer_softirq+0x6c3/0x1790
__do_softirq+0x262/0x98c
irq_exit+0x19b/0x1e0
smp_apic_timer_interrupt+0x1a3/0x610
apic_timer_interrupt+0xf/0x20
</IRQ>
See link https://syzkaller.appspot.com/bug?extid=2eeef62ee31f9460ad65 for
more details.
Fix it by using spinlock in process context instead of mutex and having
interrupt disabled in critical section.
Reported-by: syzbot+2eeef62ee31f9460ad65@syzkaller.appspotmail.com
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200113034842.435-1-zhenzhong.duan@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Michael Ellerman made a call for volunteers from NXP to maintain
this driver and I offered myself.
Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Acked-by: Timur Tabi <timur@kernel.org>
Link: https://lore.kernel.org/r/20200114110012.17351-1-laurentiu.tudor@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some of the applications like microcom do not work if
modem is disabled. To fix them we always return
TIOCM_CTS | TIOCM_DSR | TIOCM_CAR instead of 0 when
using cts_override. Make get_mctrl return actual status
when not using cts_override.
Signed-off-by: Maarten Brock <m.brock@vanmierlo.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/1574687731-21563-1-git-send-email-shubhrajyoti.datta@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
During db410c stress test and when the system is low on memory,
the UART/console becomes unresponsive and never recover back.
This has been narrowed down to the msm_start_rx_dma which does
not manage error cases correctly (e.g. dma mapping failure),
indeed, when an error happens, dma transfer is simply discarded
and so never completed, leading to unconfigured RX path.
This patch fixes this issue by switching to SW/FIFO mode in case
of DMA issue. This mainly consists in resetting the receiver to
apply RX BAM/DMA disabling change and re-enabling the RX level
and stale interrupts (previously disabled for DMA transfers).
The DMA will be re-enabled once memory is available since the
SW/FIFO read function (msm_handle_rx_dm) retries to start dma
on completion.
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1578646684-17379-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The 8250 driver can probe for many variants of the venerable 16550A
serial port. Some of those probes involve long (20ms) mdelay calls,
which delay system boot. Modern systems and virtual machines don't have
those variants.
Provide a Kconfig option to disable probes for 16550A variants.
Disabling this speeds up the boot of a virtual machine with a serial
console by more than 20ms (a substantial fraction of the ~100ms needed
to boot a carefully configured VM).
Before:
[ +0.021919] 00:04: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
After:
[ +0.000097] 00:04: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Link: https://lore.kernel.org/r/20200111022513.GA166267@localhost
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
