From: Dan Williams <dan.j.williams@intel.com>
To: linux-sh@vger.kernel.org
Subject: Re: [PATCH 3/3 v2] sh: implement DMA_SLAVE capability in SH dmaengine
Date: Wed, 03 Feb 2010 00:36:48 +0000 [thread overview]
Message-ID: <4B68C520.5000607@intel.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1001190825120.4607@axis700.grange>
Dan Williams wrote:
> Guennadi Liakhovetski wrote:
>> Tested to work with a SIU ASoC driver on sh7722 (migor).
>>
>> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
>> ---
> [..]
>> + /*
>> + * Called under dma_list_mutex, take care to perform all slave channel
>> + * ID manipulations under that lock.
>> + */
>
> Not that I think we will ever see scalability patches aimed at breaking
> up the "big dma_list_mutex lock", but it makes me a bit uneasy that this
> relies on an internal implementation detail of dmaengine. Please add a
> private lock here.
>
...or perhaps change the comment to say that this relies on the
guarantee from dmaengine that alloc_chan_resources never runs
concurrently with itself or free_chan_resources. Which is an externally
visible guarantee of dmaengine.
--
Dan
prev parent reply other threads:[~2010-02-03 0:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-19 7:27 [PATCH 3/3 v2] sh: implement DMA_SLAVE capability in SH dmaengine Guennadi Liakhovetski
2010-02-01 19:05 ` Guennadi Liakhovetski
2010-02-03 0:34 ` Dan Williams
2010-02-03 0:36 ` Dan Williams [this message]
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