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dmaengine: doc: ReSTize dmatest doc
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This converts and moves dmatest file with some format
changes for RST style

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Vinod Koul authored and Jonathan Corbet committed Nov 5, 2017
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@@ -1,46 +1,55 @@
DMA Test Guide
==============
==============
DMA Test Guide
==============

Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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
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...
Part 2 - When dmatest is built as a module
==========================================

Example of usage:
% modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1
Example of usage: ::

...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
% modprobe dmatest channel=dma0chan0 timeout=2000 iterations=1 run=1

...or on the kernel command line:
...or: ::

dmatest.channel=dma0chan0 dmatest.timeout=2000 dmatest.iterations=1 dmatest.run=1
% 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

Hint: available channel list could be extracted by running the following
command:
% ls -1 /sys/class/dma/
...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
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
Expand All @@ -50,43 +59,52 @@ 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
Example: ::

% modprobe dmatest run=1 iterations=42 wait=1
% modprobe -r dmatest

Part 3 - When built-in in the kernel...
...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/*
case. You always could check them at run-time by running ::

% grep -H . /sys/module/dmatest/parameters/*

Part 4 - Gathering the test results
Part 4 - Gathering the test results
===================================

Test results are printed to the kernel log buffer with the format:
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>)"
"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)
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)
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.
10 changes: 10 additions & 0 deletions Documentation/driver-api/dmaengine/index.rst
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Expand Up @@ -27,6 +27,16 @@ API of the DMAEngine. This is applicable only for slave DMA usage only.

client

DMA Test documentation
----------------------

This book introduces how to test DMA drivers using dmatest module.

.. toctree::
:maxdepth: 1

dmatest

.. only:: subproject

Indices
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