mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-18 15:46:42 +07:00
93 lines
3.4 KiB
Plaintext
93 lines
3.4 KiB
Plaintext
DMA Test Guide
|
|
==============
|
|
|
|
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
|
|
|
|
This small document introduces how to test DMA drivers using dmatest module.
|
|
|
|
Part 1 - How to build the test module
|
|
|
|
The menuconfig contains an option that could be found by following path:
|
|
Device Drivers -> DMA Engine support -> DMA Test client
|
|
|
|
In the configuration file the option called CONFIG_DMATEST. The dmatest could
|
|
be built as module or inside kernel. Let's consider those cases.
|
|
|
|
Part 2 - When dmatest is built as a module...
|
|
|
|
Example of usage:
|
|
% modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1
|
|
|
|
...or:
|
|
% modprobe dmatest
|
|
% echo dma0chan0 > /sys/module/dmatest/parameters/channel
|
|
% echo 2000 > /sys/module/dmatest/parameters/timeout
|
|
% echo 1 > /sys/module/dmatest/parameters/iterations
|
|
% echo 1 > /sys/module/dmatest/parameters/run
|
|
|
|
...or on the kernel command line:
|
|
|
|
dmatest.channel=dma0chan0 dmatest.timeout=2000 dmatest.iterations=1 dmatest.run=1
|
|
|
|
Hint: available channel list could be extracted by running the following
|
|
command:
|
|
% ls -1 /sys/class/dma/
|
|
|
|
Once started a message like "dmatest: Started 1 threads using dma0chan0" is
|
|
emitted. After that only test failure messages are reported until the test
|
|
stops.
|
|
|
|
Note that running a new test will not stop any in progress test.
|
|
|
|
The following command returns the state of the test.
|
|
% cat /sys/module/dmatest/parameters/run
|
|
|
|
To wait for test completion userpace can poll 'run' until it is false, or use
|
|
the wait parameter. Specifying 'wait=1' when loading the module causes module
|
|
initialization to pause until a test run has completed, while reading
|
|
/sys/module/dmatest/parameters/wait waits for any running test to complete
|
|
before returning. For example, the following scripts wait for 42 tests
|
|
to complete before exiting. Note that if 'iterations' is set to 'infinite' then
|
|
waiting is disabled.
|
|
|
|
Example:
|
|
% modprobe dmatest run=1 iterations=42 wait=1
|
|
% modprobe -r dmatest
|
|
...or:
|
|
% modprobe dmatest run=1 iterations=42
|
|
% cat /sys/module/dmatest/parameters/wait
|
|
% modprobe -r dmatest
|
|
|
|
Part 3 - When built-in in the kernel...
|
|
|
|
The module parameters that is supplied to the kernel command line will be used
|
|
for the first performed test. After user gets a control, the test could be
|
|
re-run with the same or different parameters. For the details see the above
|
|
section "Part 2 - When dmatest is built as a module..."
|
|
|
|
In both cases the module parameters are used as the actual values for the test
|
|
case. You always could check them at run-time by running
|
|
% grep -H . /sys/module/dmatest/parameters/*
|
|
|
|
Part 4 - Gathering the test results
|
|
|
|
Test results are printed to the kernel log buffer with the format:
|
|
|
|
"dmatest: result <channel>: <test id>: '<error msg>' with src_off=<val> dst_off=<val> len=<val> (<err code>)"
|
|
|
|
Example of output:
|
|
% dmesg | tail -n 1
|
|
dmatest: result dma0chan0-copy0: #1: No errors with src_off=0x7bf dst_off=0x8ad len=0x3fea (0)
|
|
|
|
The message format is unified across the different types of errors. A number in
|
|
the parens represents additional information, e.g. error code, error counter,
|
|
or status. A test thread also emits a summary line at completion listing the
|
|
number of tests executed, number that failed, and a result code.
|
|
|
|
Example:
|
|
% dmesg | tail -n 1
|
|
dmatest: dma0chan0-copy0: summary 1 test, 0 failures 1000 iops 100000 KB/s (0)
|
|
|
|
The details of a data miscompare error are also emitted, but do not follow the
|
|
above format.
|