dmatest: gather test results in the linked list

The patch provides a storage for the test results in the linked list. The
gathered data could be used after test is done.

The new file 'results' represents gathered data of the in progress test. The
messages collected are printed to the kernel log as well.

Example of output:
	% cat /sys/kernel/debug/dmatest/results
	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.

Note that the buffer comparison is done in the old way, i.e. data is not
collected and just printed out.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/Documentation/dmatest.txt b/Documentation/dmatest.txt
index 3e17b55a8ba3..d05782b26a2e 100644
--- a/Documentation/dmatest.txt
+++ b/Documentation/dmatest.txt
@@ -58,3 +58,22 @@ the above section "Part 2 - When dmatest is built as a module..."
 In both cases the module parameters are used as initial 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
+
+The module provides a storage for the test results in the memory. The gathered
+data could be used after test is done.
+
+The special file 'results' in the debugfs represents gathered data of the in
+progress test. The messages collected are printed to the kernel log as well.
+
+Example of output:
+        % cat /sys/kernel/debug/dmatest/results
+        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.
+
+Note that the buffer comparison is done in the old way, i.e. data is not
+collected and just printed out.