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Andy Shevchenko851b7e12013-03-04 11:09:30 +02001 DMA Test Guide
2 ==============
3
4 Andy Shevchenko <andriy.shevchenko@linux.intel.com>
5
6This small document introduces how to test DMA drivers using dmatest module.
7
8 Part 1 - How to build the test module
9
10The menuconfig contains an option that could be found by following path:
11 Device Drivers -> DMA Engine support -> DMA Test client
12
13In the configuration file the option called CONFIG_DMATEST. The dmatest could
14be built as module or inside kernel. Let's consider those cases.
15
16 Part 2 - When dmatest is built as a module...
17
Andy Shevchenko851b7e12013-03-04 11:09:30 +020018Example of usage:
Dan Williamsa310d032013-11-06 16:30:01 -080019 % modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1
20
21...or:
22 % modprobe dmatest
Andy Shevchenkoa6c268d2013-07-23 18:36:46 +030023 % echo dma0chan0 > /sys/module/dmatest/parameters/channel
24 % echo 2000 > /sys/module/dmatest/parameters/timeout
25 % echo 1 > /sys/module/dmatest/parameters/iterations
Dan Williamsa310d032013-11-06 16:30:01 -080026 % echo 1 > /sys/module/dmatest/parameters/run
27
28...or on the kernel command line:
29
30 dmatest.channel=dma0chan0 dmatest.timeout=2000 dmatest.iterations=1 dmatest.run=1
Andy Shevchenko851b7e12013-03-04 11:09:30 +020031
32Hint: available channel list could be extracted by running the following
33command:
34 % ls -1 /sys/class/dma/
35
Dan Williams872f05c2013-11-06 16:29:58 -080036Once started a message like "dmatest: Started 1 threads using dma0chan0" is
37emitted. After that only test failure messages are reported until the test
38stops.
Andy Shevchenko851b7e12013-03-04 11:09:30 +020039
Andy Shevchenkobcc567e2013-05-23 14:29:53 +030040Note that running a new test will not stop any in progress test.
Andy Shevchenko851b7e12013-03-04 11:09:30 +020041
Andy Shevchenko3e5ccd82013-03-04 11:09:31 +020042The following command should return actual state of the test.
43 % cat /sys/kernel/debug/dmatest/run
44
45To wait for test done the user may perform a busy loop that checks the state.
46
Dan Williamsa310d032013-11-06 16:30:01 -080047 % while [ $(cat /sys/module/dmatest/parameters/run) = "Y" ]
Andy Shevchenko3e5ccd82013-03-04 11:09:31 +020048 > do
49 > echo -n "."
50 > sleep 1
51 > done
52 > echo
53
Andy Shevchenko851b7e12013-03-04 11:09:30 +020054 Part 3 - When built-in in the kernel...
55
56The module parameters that is supplied to the kernel command line will be used
57for the first performed test. After user gets a control, the test could be
Andy Shevchenkobcc567e2013-05-23 14:29:53 +030058re-run with the same or different parameters. For the details see the above
59section "Part 2 - When dmatest is built as a module..."
Andy Shevchenko851b7e12013-03-04 11:09:30 +020060
Andy Shevchenkoa6c268d2013-07-23 18:36:46 +030061In both cases the module parameters are used as the actual values for the test
62case. You always could check them at run-time by running
Andy Shevchenko851b7e12013-03-04 11:09:30 +020063 % grep -H . /sys/module/dmatest/parameters/*
Andy Shevchenko95019c82013-03-04 11:09:33 +020064
65 Part 4 - Gathering the test results
66
Dan Williams872f05c2013-11-06 16:29:58 -080067Test results are printed to the kernel log buffer with the format:
Andy Shevchenko95019c82013-03-04 11:09:33 +020068
Dan Williams872f05c2013-11-06 16:29:58 -080069"dmatest: result <channel>: <test id>: '<error msg>' with src_off=<val> dst_off=<val> len=<val> (<err code>)"
Andy Shevchenko95019c82013-03-04 11:09:33 +020070
71Example of output:
Dan Williams872f05c2013-11-06 16:29:58 -080072 % dmesg | tail -n 1
73 dmatest: result dma0chan0-copy0: #1: No errors with src_off=0x7bf dst_off=0x8ad len=0x3fea (0)
Andy Shevchenko95019c82013-03-04 11:09:33 +020074
75The message format is unified across the different types of errors. A number in
76the parens represents additional information, e.g. error code, error counter,
Dan Williams872f05c2013-11-06 16:29:58 -080077or status. A test thread also emits a summary line at completion listing the
78number of tests executed, number that failed, and a result code.
Andy Shevchenko95019c82013-03-04 11:09:33 +020079
Dan Williams86727442013-11-06 16:30:07 -080080Example:
81 % dmesg | tail -n 1
82 dmatest: dma3chan0-copy0: summary 400000 tests, 0 failures iops: 61524 KB/s 246098 (0)
83
Dan Williams872f05c2013-11-06 16:29:58 -080084The details of a data miscompare error are also emitted, but do not follow the
85above format.