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 number in
103the parens represents additional information, e.g. error code, error counter,
104or status. A test thread also emits a summary line at completion listing the
105number of tests executed, number that failed, and a result code.
106
107Example::
108
109    % dmesg | tail -n 1
110    dmatest: dma0chan0-copy0: summary 1 test, 0 failures 1000 iops 100000 KB/s (0)
111
112The details of a data miscompare error are also emitted, but do not follow the
113above format.
114