| Andy Shevchenko | 851b7e1 | 2013-03-04 11:09:30 +0200 | [diff] [blame^] | 1 | DMA Test Guide |
| 2 | ============== |
| 3 | |
| 4 | Andy Shevchenko <andriy.shevchenko@linux.intel.com> |
| 5 | |
| 6 | This small document introduces how to test DMA drivers using dmatest module. |
| 7 | |
| 8 | Part 1 - How to build the test module |
| 9 | |
| 10 | The menuconfig contains an option that could be found by following path: |
| 11 | Device Drivers -> DMA Engine support -> DMA Test client |
| 12 | |
| 13 | In the configuration file the option called CONFIG_DMATEST. The dmatest could |
| 14 | be built as module or inside kernel. Let's consider those cases. |
| 15 | |
| 16 | Part 2 - When dmatest is built as a module... |
| 17 | |
| 18 | After mounting debugfs and loading the module, the /sys/kernel/debug/dmatest |
| 19 | folder with nodes will be created. They are the same as module parameters with |
| 20 | addition of the 'run' node that controls run and stop phases of the test. |
| 21 | |
| 22 | Note that in this case test will not run on load automatically. |
| 23 | |
| 24 | Example of usage: |
| 25 | % echo dma0chan0 > /sys/kernel/debug/dmatest/channel |
| 26 | % echo 2000 > /sys/kernel/debug/dmatest/timeout |
| 27 | % echo 1 > /sys/kernel/debug/dmatest/iterations |
| 28 | % echo 1 > /sys/kernel/debug/dmatest/run |
| 29 | |
| 30 | Hint: available channel list could be extracted by running the following |
| 31 | command: |
| 32 | % ls -1 /sys/class/dma/ |
| 33 | |
| 34 | After a while you will start to get messages about current status or error like |
| 35 | in the original code. |
| 36 | |
| 37 | Note that running a new test will stop any in progress test. |
| 38 | |
| 39 | Part 3 - When built-in in the kernel... |
| 40 | |
| 41 | The module parameters that is supplied to the kernel command line will be used |
| 42 | for the first performed test. After user gets a control, the test could be |
| 43 | interrupted or re-run with same or different parameters. For the details see |
| 44 | the above section "Part 2 - When dmatest is built as a module..." |
| 45 | |
| 46 | In both cases the module parameters are used as initial values for the test case. |
| 47 | You always could check them at run-time by running |
| 48 | % grep -H . /sys/module/dmatest/parameters/* |