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dmaengine: Documentation: Add documentation for multi chan testing
Modify documentation to add multi channel testing support. Signed-off-by: Seraj Alijan <seraj.alijan@sondrel.com> Signed-off-by: Vinod Koul <vkoul@kernel.org>
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@ -26,28 +26,43 @@ Part 2 - When dmatest is built as a module
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Example of usage::
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% modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1
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% modprobe dmatest timeout=2000 iterations=1 channel=dma0chan0 run=1
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...or::
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% modprobe dmatest
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% echo dma0chan0 > /sys/module/dmatest/parameters/channel
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% echo 2000 > /sys/module/dmatest/parameters/timeout
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% echo 1 > /sys/module/dmatest/parameters/iterations
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% echo dma0chan0 > /sys/module/dmatest/parameters/channel
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% echo 1 > /sys/module/dmatest/parameters/run
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...or on the kernel command line::
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dmatest.channel=dma0chan0 dmatest.timeout=2000 dmatest.iterations=1 dmatest.run=1
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dmatest.timeout=2000 dmatest.iterations=1 dmatest.channel=dma0chan0 dmatest.run=1
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Example of multi-channel test usage:
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% modprobe dmatest
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% echo 2000 > /sys/module/dmatest/parameters/timeout
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% echo 1 > /sys/module/dmatest/parameters/iterations
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% echo dma0chan0 > /sys/module/dmatest/parameters/channel
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% echo dma0chan1 > /sys/module/dmatest/parameters/channel
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% echo dma0chan2 > /sys/module/dmatest/parameters/channel
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% echo 1 > /sys/module/dmatest/parameters/run
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Note: the channel parameter should always be the last parameter set prior to
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running the test (setting run=1), this is because upon setting the channel
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parameter, that specific channel is requested using the dmaengine and a thread
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is created with the existing parameters. This thread is set as pending
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and will be executed once run is set to 1. Any parameters set after the thread
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is created are not applied.
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.. hint::
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available channel list could be extracted by running the following command::
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% ls -1 /sys/class/dma/
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Once started a message like "dmatest: Started 1 threads using dma0chan0" is
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emitted. After that only test failure messages are reported until the test
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stops.
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Once started a message like " dmatest: Added 1 threads using dma0chan0" is
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emitted. A thread for that specific channel is created and is now pending, the
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pending thread is started once run is to 1.
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Note that running a new test will not stop any in progress test.
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@ -112,3 +127,85 @@ Example::
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The details of a data miscompare error are also emitted, but do not follow the
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above format.
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Part 5 - Handling channel allocation
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====================================
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Allocating Channels
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-------------------
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Channels are required to be configured prior to starting the test run.
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Attempting to run the test without configuring the channels will fail.
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Example::
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% echo 1 > /sys/module/dmatest/parameters/run
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dmatest: Could not start test, no channels configured
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Channels are registered using the "channel" parameter. Channels can be requested by their
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name, once requested, the channel is registered and a pending thread is added to the test list.
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Example::
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% echo dma0chan2 > /sys/module/dmatest/parameters/channel
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dmatest: Added 1 threads using dma0chan2
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More channels can be added by repeating the example above.
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Reading back the channel parameter will return the name of last channel that was added successfully.
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Example::
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% echo dma0chan1 > /sys/module/dmatest/parameters/channel
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dmatest: Added 1 threads using dma0chan1
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% echo dma0chan2 > /sys/module/dmatest/parameters/channel
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dmatest: Added 1 threads using dma0chan2
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% cat /sys/module/dmatest/parameters/channel
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dma0chan2
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Another method of requesting channels is to request a channel with an empty string, Doing so
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will request all channels available to be tested:
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Example::
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% echo "" > /sys/module/dmatest/parameters/channel
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dmatest: Added 1 threads using dma0chan0
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dmatest: Added 1 threads using dma0chan3
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dmatest: Added 1 threads using dma0chan4
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dmatest: Added 1 threads using dma0chan5
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dmatest: Added 1 threads using dma0chan6
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dmatest: Added 1 threads using dma0chan7
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dmatest: Added 1 threads using dma0chan8
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At any point during the test configuration, reading the "test_list" parameter will
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print the list of currently pending tests.
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Example::
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% cat /sys/module/dmatest/parameters/test_list
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dmatest: 1 threads using dma0chan0
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dmatest: 1 threads using dma0chan3
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dmatest: 1 threads using dma0chan4
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dmatest: 1 threads using dma0chan5
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dmatest: 1 threads using dma0chan6
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dmatest: 1 threads using dma0chan7
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dmatest: 1 threads using dma0chan8
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Note: Channels will have to be configured for each test run as channel configurations do not
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carry across to the next test run.
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Releasing Channels
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-------------------
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Channels can be freed by setting run to 0.
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Example::
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% echo dma0chan1 > /sys/module/dmatest/parameters/channel
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dmatest: Added 1 threads using dma0chan1
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% cat /sys/class/dma/dma0chan1/in_use
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1
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% echo 0 > /sys/module/dmatest/parameters/run
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% cat /sys/class/dma/dma0chan1/in_use
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0
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Channels allocated by previous test runs are automatically freed when a new
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channel is requested after completing a successful test run.
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