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 (new in the 5.0 kernel)::
50 % echo 2000 > /sys/module/dmatest/parameters/timeout
51 % echo 1 > /sys/module/dmatest/parameters/iterations
52 % echo dma0chan0 > /sys/module/dmatest/parameters/channel
53 % echo dma0chan1 > /sys/module/dmatest/parameters/channel
54 % echo dma0chan2 > /sys/module/dmatest/parameters/channel
55 % echo 1 > /sys/module/dmatest/parameters/run
58 For all tests, starting in the 5.0 kernel, either single- or multi-channel,
59 the channel parameter(s) must be set after all other parameters. It is at
60 that time that the existing parameter values are acquired for use by the
61 thread(s). All other parameters are shared. Therefore, if changes are made
62 to any of the other parameters, and an additional channel specified, the
63 (shared) parameters used for all threads will use the new values.
64 After the channels are specified, each thread is set as pending. All threads
65 begin execution when the run parameter is set to 1.
68 A list of available channels can be found by running the following command::
70 % ls -1 /sys/class/dma/
72 Once started a message like " dmatest: Added 1 threads using dma0chan0" is
73 emitted. A thread for that specific channel is created and is now pending, the
74 pending thread is started once run is to 1.
76 Note that running a new test will not stop any in progress test.
78 The following command returns the state of the test. ::
80 % cat /sys/module/dmatest/parameters/run
82 To wait for test completion userpace can poll 'run' until it is false, or use
83 the wait parameter. Specifying 'wait=1' when loading the module causes module
84 initialization to pause until a test run has completed, while reading
85 /sys/module/dmatest/parameters/wait waits for any running test to complete
86 before returning. For example, the following scripts wait for 42 tests
87 to complete before exiting. Note that if 'iterations' is set to 'infinite' then
92 % modprobe dmatest run=1 iterations=42 wait=1
97 % modprobe dmatest run=1 iterations=42
98 % cat /sys/module/dmatest/parameters/wait
101 Part 3 - When built-in in the kernel
102 ====================================
104 The module parameters that is supplied to the kernel command line will be used
105 for the first performed test. After user gets a control, the test could be
106 re-run with the same or different parameters. For the details see the above
107 section `Part 2 - When dmatest is built as a module`_.
109 In both cases the module parameters are used as the actual values for the test
110 case. You always could check them at run-time by running ::
112 % grep -H . /sys/module/dmatest/parameters/*
114 Part 4 - Gathering the test results
115 ===================================
117 Test results are printed to the kernel log buffer with the format::
119 "dmatest: result <channel>: <test id>: '<error msg>' with src_off=<val> dst_off=<val> len=<val> (<err code>)"
124 dmatest: result dma0chan0-copy0: #1: No errors with src_off=0x7bf dst_off=0x8ad len=0x3fea (0)
126 The message format is unified across the different types of errors. A
127 number in the parentheses represents additional information, e.g. error
128 code, error counter, or status. A test thread also emits a summary line at
129 completion listing the number of tests executed, number that failed, and a
135 dmatest: dma0chan0-copy0: summary 1 test, 0 failures 1000 iops 100000 KB/s (0)
137 The details of a data miscompare error are also emitted, but do not follow the
140 Part 5 - Handling channel allocation
141 ====================================
146 Channels do not need to be configured prior to starting a test run. Attempting
147 to run the test without configuring the channels will result in testing any
148 channels that are available.
152 % echo 1 > /sys/module/dmatest/parameters/run
153 dmatest: No channels configured, continue with any
155 Channels are registered using the "channel" parameter. Channels can be requested by their
156 name, once requested, the channel is registered and a pending thread is added to the test list.
160 % echo dma0chan2 > /sys/module/dmatest/parameters/channel
161 dmatest: Added 1 threads using dma0chan2
163 More channels can be added by repeating the example above.
164 Reading back the channel parameter will return the name of last channel that was added successfully.
168 % echo dma0chan1 > /sys/module/dmatest/parameters/channel
169 dmatest: Added 1 threads using dma0chan1
170 % echo dma0chan2 > /sys/module/dmatest/parameters/channel
171 dmatest: Added 1 threads using dma0chan2
172 % cat /sys/module/dmatest/parameters/channel
175 Another method of requesting channels is to request a channel with an empty string, Doing so
176 will request all channels available to be tested:
180 % echo "" > /sys/module/dmatest/parameters/channel
181 dmatest: Added 1 threads using dma0chan0
182 dmatest: Added 1 threads using dma0chan3
183 dmatest: Added 1 threads using dma0chan4
184 dmatest: Added 1 threads using dma0chan5
185 dmatest: Added 1 threads using dma0chan6
186 dmatest: Added 1 threads using dma0chan7
187 dmatest: Added 1 threads using dma0chan8
189 At any point during the test configuration, reading the "test_list" parameter will
190 print the list of currently pending tests.
194 % cat /sys/module/dmatest/parameters/test_list
195 dmatest: 1 threads using dma0chan0
196 dmatest: 1 threads using dma0chan3
197 dmatest: 1 threads using dma0chan4
198 dmatest: 1 threads using dma0chan5
199 dmatest: 1 threads using dma0chan6
200 dmatest: 1 threads using dma0chan7
201 dmatest: 1 threads using dma0chan8
203 Note: Channels will have to be configured for each test run as channel configurations do not
204 carry across to the next test run.
209 Channels can be freed by setting run to 0.
213 % echo dma0chan1 > /sys/module/dmatest/parameters/channel
214 dmatest: Added 1 threads using dma0chan1
215 % cat /sys/class/dma/dma0chan1/in_use
217 % echo 0 > /sys/module/dmatest/parameters/run
218 % cat /sys/class/dma/dma0chan1/in_use
221 Channels allocated by previous test runs are automatically freed when a new
222 channel is requested after completing a successful test run.