diff options
| author | Hook, Gary <Gary.Hook@amd.com> | 2019-06-24 18:35:01 +0000 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2019-07-05 12:21:01 +0530 |
| commit | 9dcb98a29b6e81394fa33ca984f3aaad4d0d1393 (patch) | |
| tree | 9c7557e222cd06bb34a85d0278b9f70c11977e0c | |
| parent | 3145d73e69ba0ab58cb302d3e6a80232bf373b7e (diff) | |
Documentation: dmaengine: clean up description of dmatest usage
Fix the formatting of the multi-channel test usage example. Call out
the note about parameter ordering and add detail on the settings of
parameters for the new version of dmatest.
Fixes: f80f9988a26d7 ("dmaengine: Documentation: Add documentation for multi chan testing")
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
| -rw-r--r-- | Documentation/driver-api/dmaengine/dmatest.rst | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/Documentation/driver-api/dmaengine/dmatest.rst b/Documentation/driver-api/dmaengine/dmatest.rst index e78d070bb468..ee268d445d38 100644 --- a/Documentation/driver-api/dmaengine/dmatest.rst +++ b/Documentation/driver-api/dmaengine/dmatest.rst @@ -44,7 +44,8 @@ Example of usage:: dmatest.timeout=2000 dmatest.iterations=1 dmatest.channel=dma0chan0 dmatest.run=1 -Example of multi-channel test usage: +Example of multi-channel test usage (new in the 5.0 kernel):: + % modprobe dmatest % echo 2000 > /sys/module/dmatest/parameters/timeout % echo 1 > /sys/module/dmatest/parameters/iterations @@ -53,15 +54,18 @@ Example of multi-channel test usage: % echo dma0chan2 > /sys/module/dmatest/parameters/channel % echo 1 > /sys/module/dmatest/parameters/run -Note: the channel parameter should always be the last parameter set prior to -running the test (setting run=1), this is because upon setting the channel -parameter, that specific channel is requested using the dmaengine and a thread -is created with the existing parameters. This thread is set as pending -and will be executed once run is set to 1. Any parameters set after the thread -is created are not applied. +.. note:: + For all tests, starting in the 5.0 kernel, either single- or multi-channel, + the channel parameter(s) must be set after all other parameters. It is at + that time that the existing parameter values are acquired for use by the + thread(s). All other parameters are shared. Therefore, if changes are made + to any of the other parameters, and an additional channel specified, the + (shared) parameters used for all threads will use the new values. + After the channels are specified, each thread is set as pending. All threads + begin execution when the run parameter is set to 1. .. hint:: - available channel list could be extracted by running the following command:: + A list of available channels can be found by running the following command:: % ls -1 /sys/class/dma/ @@ -204,6 +208,7 @@ Releasing Channels Channels can be freed by setting run to 0. Example:: + % echo dma0chan1 > /sys/module/dmatest/parameters/channel dmatest: Added 1 threads using dma0chan1 % cat /sys/class/dma/dma0chan1/in_use |