Merge branch 'topic/doc' into for-linus
This commit is contained in:
commit
7fc3b3f946
|
@ -37,8 +37,8 @@ The slave DMA usage consists of following steps:
|
|||
2. Set slave and controller specific parameters
|
||||
|
||||
Next step is always to pass some specific information to the DMA
|
||||
driver. Most of the generic information which a slave DMA can use
|
||||
is in struct dma_slave_config. This allows the clients to specify
|
||||
driver. Most of the generic information which a slave DMA can use
|
||||
is in struct dma_slave_config. This allows the clients to specify
|
||||
DMA direction, DMA addresses, bus widths, DMA burst lengths etc
|
||||
for the peripheral.
|
||||
|
||||
|
@ -52,7 +52,7 @@ The slave DMA usage consists of following steps:
|
|||
struct dma_slave_config *config)
|
||||
|
||||
Please see the dma_slave_config structure definition in dmaengine.h
|
||||
for a detailed explanation of the struct members. Please note
|
||||
for a detailed explanation of the struct members. Please note
|
||||
that the 'direction' member will be going away as it duplicates the
|
||||
direction given in the prepare call.
|
||||
|
||||
|
@ -101,7 +101,7 @@ The slave DMA usage consists of following steps:
|
|||
desc = dmaengine_prep_slave_sg(chan, sgl, nr_sg, direction, flags);
|
||||
|
||||
Once a descriptor has been obtained, the callback information can be
|
||||
added and the descriptor must then be submitted. Some DMA engine
|
||||
added and the descriptor must then be submitted. Some DMA engine
|
||||
drivers may hold a spinlock between a successful preparation and
|
||||
submission so it is important that these two operations are closely
|
||||
paired.
|
||||
|
@ -138,7 +138,7 @@ The slave DMA usage consists of following steps:
|
|||
activity via other DMA engine calls not covered in this document.
|
||||
|
||||
dmaengine_submit() will not start the DMA operation, it merely adds
|
||||
it to the pending queue. For this, see step 5, dma_async_issue_pending.
|
||||
it to the pending queue. For this, see step 5, dma_async_issue_pending.
|
||||
|
||||
5. Issue pending DMA requests and wait for callback notification
|
||||
|
||||
|
@ -184,13 +184,13 @@ Further APIs:
|
|||
|
||||
3. int dmaengine_resume(struct dma_chan *chan)
|
||||
|
||||
Resume a previously paused DMA channel. It is invalid to resume a
|
||||
Resume a previously paused DMA channel. It is invalid to resume a
|
||||
channel which is not currently paused.
|
||||
|
||||
4. enum dma_status dma_async_is_tx_complete(struct dma_chan *chan,
|
||||
dma_cookie_t cookie, dma_cookie_t *last, dma_cookie_t *used)
|
||||
|
||||
This can be used to check the status of the channel. Please see
|
||||
This can be used to check the status of the channel. Please see
|
||||
the documentation in include/linux/dmaengine.h for a more complete
|
||||
description of this API.
|
||||
|
||||
|
@ -200,7 +200,7 @@ Further APIs:
|
|||
|
||||
Note:
|
||||
Not all DMA engine drivers can return reliable information for
|
||||
a running DMA channel. It is recommended that DMA engine users
|
||||
a running DMA channel. It is recommended that DMA engine users
|
||||
pause or stop (via dmaengine_terminate_all()) the channel before
|
||||
using this API.
|
||||
|
||||
|
|
|
@ -34,7 +34,7 @@ command:
|
|||
% ls -1 /sys/class/dma/
|
||||
|
||||
Once started a message like "dmatest: Started 1 threads using dma0chan0" is
|
||||
emitted. After that only test failure messages are reported until the test
|
||||
emitted. After that only test failure messages are reported until the test
|
||||
stops.
|
||||
|
||||
Note that running a new test will not stop any in progress test.
|
||||
|
@ -43,11 +43,11 @@ The following command returns the state of the test.
|
|||
% cat /sys/module/dmatest/parameters/run
|
||||
|
||||
To wait for test completion userpace can poll 'run' until it is false, or use
|
||||
the wait parameter. Specifying 'wait=1' when loading the module causes module
|
||||
the wait parameter. Specifying 'wait=1' when loading the module causes module
|
||||
initialization to pause until a test run has completed, while reading
|
||||
/sys/module/dmatest/parameters/wait waits for any running test to complete
|
||||
before returning. For example, the following scripts wait for 42 tests
|
||||
to complete before exiting. Note that if 'iterations' is set to 'infinite' then
|
||||
before returning. For example, the following scripts wait for 42 tests
|
||||
to complete before exiting. Note that if 'iterations' is set to 'infinite' then
|
||||
waiting is disabled.
|
||||
|
||||
Example:
|
||||
|
@ -81,7 +81,7 @@ Example of output:
|
|||
|
||||
The message format is unified across the different types of errors. A number in
|
||||
the parens represents additional information, e.g. error code, error counter,
|
||||
or status. A test thread also emits a summary line at completion listing the
|
||||
or status. A test thread also emits a summary line at completion listing the
|
||||
number of tests executed, number that failed, and a result code.
|
||||
|
||||
Example:
|
||||
|
|
|
@ -384,7 +384,7 @@ where to put them)
|
|||
- The descriptor should be prepared for reuse by invoking
|
||||
dmaengine_desc_set_reuse() which will set DMA_CTRL_REUSE.
|
||||
- dmaengine_desc_set_reuse() will succeed only when channel support
|
||||
reusable descriptor as exhibited by capablities
|
||||
reusable descriptor as exhibited by capabilities
|
||||
- As a consequence, if a device driver wants to skip the dma_map_sg() and
|
||||
dma_unmap_sg() in between 2 transfers, because the DMA'd data wasn't used,
|
||||
it can resubmit the transfer right after its completion.
|
||||
|
|
|
@ -29,7 +29,7 @@ Constraints
|
|||
|
||||
d) Bandwidth guarantee
|
||||
The PXA architecture has 4 levels of DMAs priorities : high, normal, low.
|
||||
The high prorities get twice as much bandwidth as the normal, which get twice
|
||||
The high priorities get twice as much bandwidth as the normal, which get twice
|
||||
as much as the low priorities.
|
||||
A driver should be able to request a priority, especially the real-time
|
||||
ones such as pxa_camera with (big) throughputs.
|
||||
|
|
Loading…
Reference in a new issue