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| author | Jonathan Corbet <corbet@lwn.net> | 2019-07-22 13:42:10 -0600 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2019-07-22 13:42:10 -0600 |
| commit | e27a24210aa17b8a0cd462865130fe73afd7e001 (patch) | |
| tree | b2d7b8311d280244fad3166792e8f447081a8bc9 /Documentation/driver-api/dmaengine/dmatest.rst | |
| parent | 224d5fd43d250f850d64fb6d668114aff29d7022 (diff) | |
| parent | 5f9e832c137075045d15cd6899ab0505cfb2ca4b (diff) | |
| download | lwn-e27a24210aa17b8a0cd462865130fe73afd7e001.tar.gz lwn-e27a24210aa17b8a0cd462865130fe73afd7e001.zip | |
Merge tag 'v5.3-rc1' into docs-next
Pull in all of the massive docs changes from elsewhere.
Diffstat (limited to 'Documentation/driver-api/dmaengine/dmatest.rst')
| -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 |