5 Andy Shevchenko <andriy.shevchenko@linux.intel.com>
7 This small document introduces how to test DMA drivers using dmatest module.
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.
15 In case of any related questions use the official mailing list
16 dmaengine@vger.kernel.org.
18 Part 1 - How to build the test module
19 =====================================
21 The menuconfig contains an option that could be found by following path:
23 Device Drivers -> DMA Engine support -> DMA Test client
25 In the configuration file the option called CONFIG_DMATEST. The dmatest could
26 be built as module or inside kernel. Let's consider those cases.
28 Part 2 - When dmatest is built as a module
29 ==========================================
33 % modprobe dmatest timeout=2000 iterations=1 channel=dma0chan0 run=1
38 % echo 2000 > /sys/module/dmatest/parameters/timeout
39 % echo 1 > /sys/module/dmatest/parameters/iterations
40 % echo dma0chan0 > /sys/module/dmatest/parameters/channel
41 % echo 1 > /sys/module/dmatest/parameters/run
43 ...or on the kernel command line::
45 dmatest.timeout=2000 dmatest.iterations=1 dmatest.channel=dma0chan0 dmatest.run=1
47 Example of multi-channel test usage:
49 % echo 2000 > /sys/module/dmatest/parameters/timeout
50 % echo 1 > /sys/module/dmatest/parameters/iterations
51 % echo dma0chan0 > /sys/module/dmatest/parameters/channel
52 % echo dma0chan1 > /sys/module/dmatest/parameters/channel
53 % echo dma0chan2 > /sys/module/dmatest/parameters/channel
54 % echo 1 > /sys/module/dmatest/parameters/run
56 Note: the channel parameter should always be the last parameter set prior to
57 running the test (setting run=1), this is because upon setting the channel
58 parameter, that specific channel is requested using the dmaengine and a thread
59 is created with the existing parameters. This thread is set as pending
60 and will be executed once run is set to 1. Any parameters set after the thread
61 is created are not applied.
64 available channel list could be extracted by running the following command::
66 % ls -1 /sys/class/dma/
68 Once started a message like " dmatest: Added 1 threads using dma0chan0" is
69 emitted. A thread for that specific channel is created and is now pending, the
70 pending thread is started once run is to 1.
72 Note that running a new test will not stop any in progress test.
74 The following command returns the state of the test. ::
76 % cat /sys/module/dmatest/parameters/run
78 To wait for test completion userpace can poll 'run' until it is false, or use
79 the wait parameter. Specifying 'wait=1' when loading the module causes module
80 initialization to pause until a test run has completed, while reading
81 /sys/module/dmatest/parameters/wait waits for any running test to complete
82 before returning. For example, the following scripts wait for 42 tests
83 to complete before exiting. Note that if 'iterations' is set to 'infinite' then
88 % modprobe dmatest run=1 iterations=42 wait=1
93 % modprobe dmatest run=1 iterations=42
94 % cat /sys/module/dmatest/parameters/wait
97 Part 3 - When built-in in the kernel
98 ====================================
100 The module parameters that is supplied to the kernel command line will be used
101 for the first performed test. After user gets a control, the test could be
102 re-run with the same or different parameters. For the details see the above
103 section `Part 2 - When dmatest is built as a module`_.
105 In both cases the module parameters are used as the actual values for the test
106 case. You always could check them at run-time by running ::
108 % grep -H . /sys/module/dmatest/parameters/*
110 Part 4 - Gathering the test results
111 ===================================
113 Test results are printed to the kernel log buffer with the format::
115 "dmatest: result <channel>: <test id>: '<error msg>' with src_off=<val> dst_off=<val> len=<val> (<err code>)"
120 dmatest: result dma0chan0-copy0: #1: No errors with src_off=0x7bf dst_off=0x8ad len=0x3fea (0)
122 The message format is unified across the different types of errors. A
123 number in the parentheses represents additional information, e.g. error
124 code, error counter, or status. A test thread also emits a summary line at
125 completion listing the number of tests executed, number that failed, and a
131 dmatest: dma0chan0-copy0: summary 1 test, 0 failures 1000 iops 100000 KB/s (0)
133 The details of a data miscompare error are also emitted, but do not follow the
136 Part 5 - Handling channel allocation
137 ====================================
142 Channels are required to be configured prior to starting the test run.
143 Attempting to run the test without configuring the channels will fail.
147 % echo 1 > /sys/module/dmatest/parameters/run
148 dmatest: Could not start test, no channels configured
150 Channels are registered using the "channel" parameter. Channels can be requested by their
151 name, once requested, the channel is registered and a pending thread is added to the test list.
155 % echo dma0chan2 > /sys/module/dmatest/parameters/channel
156 dmatest: Added 1 threads using dma0chan2
158 More channels can be added by repeating the example above.
159 Reading back the channel parameter will return the name of last channel that was added successfully.
163 % echo dma0chan1 > /sys/module/dmatest/parameters/channel
164 dmatest: Added 1 threads using dma0chan1
165 % echo dma0chan2 > /sys/module/dmatest/parameters/channel
166 dmatest: Added 1 threads using dma0chan2
167 % cat /sys/module/dmatest/parameters/channel
170 Another method of requesting channels is to request a channel with an empty string, Doing so
171 will request all channels available to be tested:
175 % echo "" > /sys/module/dmatest/parameters/channel
176 dmatest: Added 1 threads using dma0chan0
177 dmatest: Added 1 threads using dma0chan3
178 dmatest: Added 1 threads using dma0chan4
179 dmatest: Added 1 threads using dma0chan5
180 dmatest: Added 1 threads using dma0chan6
181 dmatest: Added 1 threads using dma0chan7
182 dmatest: Added 1 threads using dma0chan8
184 At any point during the test configuration, reading the "test_list" parameter will
185 print the list of currently pending tests.
189 % cat /sys/module/dmatest/parameters/test_list
190 dmatest: 1 threads using dma0chan0
191 dmatest: 1 threads using dma0chan3
192 dmatest: 1 threads using dma0chan4
193 dmatest: 1 threads using dma0chan5
194 dmatest: 1 threads using dma0chan6
195 dmatest: 1 threads using dma0chan7
196 dmatest: 1 threads using dma0chan8
198 Note: Channels will have to be configured for each test run as channel configurations do not
199 carry across to the next test run.
204 Channels can be freed by setting run to 0.
207 % echo dma0chan1 > /sys/module/dmatest/parameters/channel
208 dmatest: Added 1 threads using dma0chan1
209 % cat /sys/class/dma/dma0chan1/in_use
211 % echo 0 > /sys/module/dmatest/parameters/run
212 % cat /sys/class/dma/dma0chan1/in_use
215 Channels allocated by previous test runs are automatically freed when a new
216 channel is requested after completing a successful test run.