1============== 2DMA Test Guide 3============== 4 5Andy Shevchenko <andriy.shevchenko@linux.intel.com> 6 7This small document introduces how to test DMA drivers using dmatest module. 8 9.. note:: 10 The test suite works only on the channels that have at least one 11 capability of the following: DMA_MEMCPY (memory-to-memory), DMA_MEMSET 12 (const-to-memory or memory-to-memory, when emulated), DMA_XOR, DMA_PQ. 13 14Part 1 - How to build the test module 15===================================== 16 17The menuconfig contains an option that could be found by following path: 18 19 Device Drivers -> DMA Engine support -> DMA Test client 20 21In the configuration file the option called CONFIG_DMATEST. The dmatest could 22be built as module or inside kernel. Let's consider those cases. 23 24Part 2 - When dmatest is built as a module 25========================================== 26 27Example of usage:: 28 29 % modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1 30 31...or:: 32 33 % modprobe dmatest 34 % echo dma0chan0 > /sys/module/dmatest/parameters/channel 35 % echo 2000 > /sys/module/dmatest/parameters/timeout 36 % echo 1 > /sys/module/dmatest/parameters/iterations 37 % echo 1 > /sys/module/dmatest/parameters/run 38 39...or on the kernel command line:: 40 41 dmatest.channel=dma0chan0 dmatest.timeout=2000 dmatest.iterations=1 dmatest.run=1 42 43.. hint:: 44 available channel list could be extracted by running the following command:: 45 46 % ls -1 /sys/class/dma/ 47 48Once started a message like "dmatest: Started 1 threads using dma0chan0" is 49emitted. After that only test failure messages are reported until the test 50stops. 51 52Note that running a new test will not stop any in progress test. 53 54The following command returns the state of the test. :: 55 56 % cat /sys/module/dmatest/parameters/run 57 58To wait for test completion userpace can poll 'run' until it is false, or use 59the wait parameter. Specifying 'wait=1' when loading the module causes module 60initialization to pause until a test run has completed, while reading 61/sys/module/dmatest/parameters/wait waits for any running test to complete 62before returning. For example, the following scripts wait for 42 tests 63to complete before exiting. Note that if 'iterations' is set to 'infinite' then 64waiting is disabled. 65 66Example:: 67 68 % modprobe dmatest run=1 iterations=42 wait=1 69 % modprobe -r dmatest 70 71...or:: 72 73 % modprobe dmatest run=1 iterations=42 74 % cat /sys/module/dmatest/parameters/wait 75 % modprobe -r dmatest 76 77Part 3 - When built-in in the kernel 78==================================== 79 80The module parameters that is supplied to the kernel command line will be used 81for the first performed test. After user gets a control, the test could be 82re-run with the same or different parameters. For the details see the above 83section `Part 2 - When dmatest is built as a module`_. 84 85In both cases the module parameters are used as the actual values for the test 86case. You always could check them at run-time by running :: 87 88 % grep -H . /sys/module/dmatest/parameters/* 89 90Part 4 - Gathering the test results 91=================================== 92 93Test results are printed to the kernel log buffer with the format:: 94 95 "dmatest: result <channel>: <test id>: '<error msg>' with src_off=<val> dst_off=<val> len=<val> (<err code>)" 96 97Example of output:: 98 99 % dmesg | tail -n 1 100 dmatest: result dma0chan0-copy0: #1: No errors with src_off=0x7bf dst_off=0x8ad len=0x3fea (0) 101 102The message format is unified across the different types of errors. A 103number in the parentheses represents additional information, e.g. error 104code, error counter, or status. A test thread also emits a summary line at 105completion listing the number of tests executed, number that failed, and a 106result code. 107 108Example:: 109 110 % dmesg | tail -n 1 111 dmatest: dma0chan0-copy0: summary 1 test, 0 failures 1000 iops 100000 KB/s (0) 112 113The details of a data miscompare error are also emitted, but do not follow the 114above format. 115