linux-kernel - Re: [PATCH 08/10] ASoC: ux500_pcm: Differentiate between pdata and DT initialisation

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Message-ID: <528BBE90.4020802@metafoo.de>
Date:	Tue, 19 Nov 2013 20:40:00 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Lee Jones <lee.jones@...aro.org>
CC:	Mark Brown <broonie@...nel.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linus.walleij@...aro.org, alsa-devel@...a-project.org
Subject: Re: [PATCH 08/10] ASoC: ux500_pcm: Differentiate between pdata and
 DT initialisation

On 11/19/2013 08:33 PM, Lee Jones wrote:
> On Tue, 19 Nov 2013, Mark Brown wrote:
> 
>> On Tue, Nov 19, 2013 at 11:07:47AM +0000, Lee Jones wrote:
>>
>>> require slightly different flags to inform the core that we 'are'
>>> booting with DT.
>>
>> Is there some situation when we would want to say we're booting from DT
>> when we aren't?  Just wondering about the quotes.
> 
> The quotes do 'not' mean anything special. :)
> 
>>> +static const struct snd_dmaengine_pcm_config ux500_dmaengine_of_pcm_config = {
>>> +	.pcm_hardware = &ux500_pcm_hw,
>>> +	.prealloc_buffer_size = 128 * 1024,
>>
>> You shouldn't need to set this explicitly, the generic code should be
>> able to pick a number for you - if you do need this number please
>> explain why the number was chosen in the comments (or fix the core to
>> guess better).  At the minute the core just makes up a number too but at
>> least then it's a consistent random number between platforms.
>>
>> Can you also get away without the pcm_hardware - the core should also
>> have support for discovering this by querying the DMA controller?
> 
> Despite the '+'s, I'm not actually adding these parameters, I'm
> duplicating the pdata version and removing the stuff I 'know' that's
> not required. I don't know what happens when/if these two parameters
> are removed. I can add this to my TODO when I rip out platform data
> support, which will happen when this stuff lands.
> 

I think the patch is fine for now. Once non-DT support has been removed for
ux500 we should be able to remove the whole ux500_pcm.c file (Assuming that
the ux500 DMA engine driver gains dma_slave_caps support).

- Lars
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