linux-kernel - Re: [PATCH 2/2] dma:of: Use a mutex to protect the of_dma

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Date:	Sun, 21 Apr 2013 20:18:39 -0500
From:	Jon Hunter <jon-hunter@...com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	Lars-Peter Clausen <lars@...afoo.de>,
	Vinod Koul <vinod.koul@...el.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] dma:of: Use a mutex to protect the of_dma_list


On 04/20/2013 05:38 AM, Arnd Bergmann wrote:
> On Saturday 20 April 2013, Lars-Peter Clausen wrote:
>> On 04/20/2013 12:45 AM, Jon Hunter wrote:
>>> I think that there is a problem here. For controllers using the
>>> of_dma_simple_xlate(), this will call dma_request_channel() which also
>>> uses a mutex.
>>
>> That would only be a problem if it'd use the same mutex. Holding two mutexes at
>> the same time is not a problem per se.
>>
> 
> I guess Jon originlly tried it with a spinlock as the outer lock, which indeed
> does not work, but the new version does not have this problem.

Yes the spinlock was a problem and hence for the put/get functions. Ok
so that's fine then.

Cheers
Jon
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