linux-kernel - Re: [PATCH] dmatest: masking tests for channel capabilities

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Date:	Tue, 18 Jun 2013 12:16:07 -0700
From:	Dan Williams <djbw@...com>
To:	Jubin Mehta <jubin.mehta@...el.com>
Cc:	Vinod Koul <vinod.koul@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Jon Mason <jon.mason@...el.com>
Subject: Re: [PATCH] dmatest: masking tests for channel capabilities

On Tue, Jun 18, 2013 at 10:34 AM, Jubin Mehta <jubin.mehta@...el.com> wrote:
> On Mon, Jun 17, 2013 at 02:12:51PM -0700, Dan Williams wrote:
>> [ apologies for the resend, gmail defaulted to html ]
>>
>> On Mon, Jun 17, 2013 at 2:10 PM, Dan Williams <djbw@...com> wrote:
>> >> +Example to perform only MEMCPY and PQ mode tests (0x01 | 0x04 = 0x05):
>> >> +
>> >> +        % modprobe dmatest
>> >> +        % echo dma0chan0 > /sys/kernel/debug/dmatest/channel
>> >> +        % echo 5  > /sys/kernel/debug/dmatest/cap_mask
>> >> +        % echo 1 > /sys/kernel/debug/dmatest/iterations
>> >> +        % echo 1 > /sys/kernel/debug/dmatest/run
>> >
>> >
>> > Hmmm, I should have paid more attention when the debugfs support was
>> > initially proposed for dmatest.  As it is I see duplication and
>> > configuration parameters getting out of sync with their module parameter
>> > equivalents versus just having all configuration go through module
>> > parameters.  module_param_call() can be used for the more complex options.
>> > Debugfs at this point looks like overkill for what amounts to some simple
>> > configuration variables and a result line.
>> >
>> > --
>> > Dan
>>
> Would you like to have some changes regarding the configuration
> process for the module parameters of the dmatest?

Yes, as a first step I would like to see a clean up of the the
configuration parameters to be available via
/sys/module/dmatest/parameters rather than /sys/kernel/debug/dmatest

As for "run" and "results" I see Andy's point that those are a bit
awkward as parameters.  However, we do have trace points as a more
general mechanism for dumping events and data to userspace.  If we had
/sys/module/dmatest/parameters/run with a tracepoint for the result
line does that get us everything we need for automation?  I can see
more tracepoints beng added to get some perf metrics out of the tests.
 Thoughts?

> Any other comments with respect to the patch?

How about a comma separated list of named capabilities (copy, xor, pq,
xor_val, sg... etc) rather than a mask?  If we are already not using
the dma_transaction_type values might as well use something human
readable.

--
Dan
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