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Diffstat (limited to 'Documentation/driver-api/dmaengine/dmatest.rst')
| -rw-r--r-- | Documentation/driver-api/dmaengine/dmatest.rst | 113 |
1 files changed, 107 insertions, 6 deletions
diff --git a/Documentation/driver-api/dmaengine/dmatest.rst b/Documentation/driver-api/dmaengine/dmatest.rst index 7ce5e71c353e..8d81f1a7169b 100644 --- a/Documentation/driver-api/dmaengine/dmatest.rst +++ b/Documentation/driver-api/dmaengine/dmatest.rst @@ -11,6 +11,10 @@ This small document introduces how to test DMA drivers using dmatest module. capability of the following: DMA_MEMCPY (memory-to-memory), DMA_MEMSET (const-to-memory or memory-to-memory, when emulated), DMA_XOR, DMA_PQ. +.. note:: + In case of any related questions use the official mailing list + dmaengine@vger.kernel.org. + Part 1 - How to build the test module ===================================== @@ -26,28 +30,43 @@ Part 2 - When dmatest is built as a module Example of usage:: - % modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1 + % modprobe dmatest timeout=2000 iterations=1 channel=dma0chan0 run=1 ...or:: % modprobe dmatest - % echo dma0chan0 > /sys/module/dmatest/parameters/channel % echo 2000 > /sys/module/dmatest/parameters/timeout % echo 1 > /sys/module/dmatest/parameters/iterations + % echo dma0chan0 > /sys/module/dmatest/parameters/channel % echo 1 > /sys/module/dmatest/parameters/run ...or on the kernel command line:: - dmatest.channel=dma0chan0 dmatest.timeout=2000 dmatest.iterations=1 dmatest.run=1 + dmatest.timeout=2000 dmatest.iterations=1 dmatest.channel=dma0chan0 dmatest.run=1 + +Example of multi-channel test usage: + % modprobe dmatest + % echo 2000 > /sys/module/dmatest/parameters/timeout + % echo 1 > /sys/module/dmatest/parameters/iterations + % echo dma0chan0 > /sys/module/dmatest/parameters/channel + % echo dma0chan1 > /sys/module/dmatest/parameters/channel + % 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. .. hint:: available channel list could be extracted by running the following 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 -stops. +Once started a message like " dmatest: Added 1 threads using dma0chan0" is +emitted. A thread for that specific channel is created and is now pending, the +pending thread is started once run is to 1. Note that running a new test will not stop any in progress test. @@ -112,3 +131,85 @@ Example:: The details of a data miscompare error are also emitted, but do not follow the above format. + +Part 5 - Handling channel allocation +==================================== + +Allocating Channels +------------------- + +Channels are required to be configured prior to starting the test run. +Attempting to run the test without configuring the channels will fail. + +Example:: + + % echo 1 > /sys/module/dmatest/parameters/run + dmatest: Could not start test, no channels configured + +Channels are registered using the "channel" parameter. Channels can be requested by their +name, once requested, the channel is registered and a pending thread is added to the test list. + +Example:: + + % echo dma0chan2 > /sys/module/dmatest/parameters/channel + dmatest: Added 1 threads using dma0chan2 + +More channels can be added by repeating the example above. +Reading back the channel parameter will return the name of last channel that was added successfully. + +Example:: + + % echo dma0chan1 > /sys/module/dmatest/parameters/channel + dmatest: Added 1 threads using dma0chan1 + % echo dma0chan2 > /sys/module/dmatest/parameters/channel + dmatest: Added 1 threads using dma0chan2 + % cat /sys/module/dmatest/parameters/channel + dma0chan2 + +Another method of requesting channels is to request a channel with an empty string, Doing so +will request all channels available to be tested: + +Example:: + + % echo "" > /sys/module/dmatest/parameters/channel + dmatest: Added 1 threads using dma0chan0 + dmatest: Added 1 threads using dma0chan3 + dmatest: Added 1 threads using dma0chan4 + dmatest: Added 1 threads using dma0chan5 + dmatest: Added 1 threads using dma0chan6 + dmatest: Added 1 threads using dma0chan7 + dmatest: Added 1 threads using dma0chan8 + +At any point during the test configuration, reading the "test_list" parameter will +print the list of currently pending tests. + +Example:: + + % cat /sys/module/dmatest/parameters/test_list + dmatest: 1 threads using dma0chan0 + dmatest: 1 threads using dma0chan3 + dmatest: 1 threads using dma0chan4 + dmatest: 1 threads using dma0chan5 + dmatest: 1 threads using dma0chan6 + dmatest: 1 threads using dma0chan7 + dmatest: 1 threads using dma0chan8 + +Note: Channels will have to be configured for each test run as channel configurations do not +carry across to the next test run. + +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 + 1 + % echo 0 > /sys/module/dmatest/parameters/run + % cat /sys/class/dma/dma0chan1/in_use + 0 + +Channels allocated by previous test runs are automatically freed when a new +channel is requested after completing a successful test run. |