RE: [alsa-devel] [PATCH 1/4] ASOC: Blackfin driver for ALSA SoC framework

[Cliff Cai <xcahua@hotmail.com>]

> Date: Wed, 3 Sep 2008 11:38:52 +0100
> From: broonie@sirena.org.uk
> To: Cliff.Cai@analog.com
> CC: linux-kernel@vger.kernel.org; cooloney@kernel.org; alsa-devel@alsa-project.org; lrg@kernel.org
> Subject: Re: [alsa-devel] [PATCH 1/4] ASOC: Blackfin driver for ALSA SoC framework
>
> On Wed, Sep 03, 2008 at 12:09:49PM +0800, Cai, Cliff wrote:
>
> Cliff, please fix your mail client configuration - the formatting of
> your reply makes little (if any) distinction between the text of my
> original mail which makes your message difficult to read.
>
>> -----Original Message-----
>> From: Mark Brown [mailto:broonie@sirena.org.uk]
>> Sent: Wednesday, August 27, 2008 9:49 PM
>> To: Bryan Wu
>> Cc: perex@perex.cz; lrg@kernel.org; alsa-devel@alsa-project.org;
>> linux-kernel@vger.kernel.org; Cliff Cai
>> Subject: Re: [PATCH 1/4] ASOC: Blackfin driver for ALSA SoC framework
>
>> On Wed, Aug 27, 2008 at 05:39:25PM +0800, Bryan Wu wrote:
>>> From: Cliff Cai 
>
>>>Again, odd blank lines and presumably there needs to be something to
>> undo things on error?
>
>> t's not necessary to do anything else on error, these functions only set
>> registers.
>
> And none of these settings will leave things so that the port looks busy
> or anything like that?


No,they are called just to configure somthing but won't start it,it only fails when the port is busy.


>
>> TX and RX Clocks are also not independent,currently,in order to
>> implement full duplex,we have to enable both RX and TX side even if
>> there is only a steam is opened,
>> And make the other side running on a dummy buffer,so all registers
>> cann't be configured any more. when the second stream is opened we just
>> switch the DMA form dummy buffer to the normal data buffer.
>
> Right, in that case your driver should use constraints to stop
> applications trying to configure the capture and playback sides
> differently.
>
>>>I'm also not seeing the code that configures the sample rate anywhere -
>> but then it looks like the driver only support slave mode ATM? That's
>> what the machine driver is
>>>using. There should still be a set_fmt() to document what's supported
>> if nothing else.
>
>> Yes ,the codec runs in master mode and provides bit clock..Do you mean
>> just implement a dummy set_fmt() with comments for CPU DAI,
>
> It shouldn't just be a dummy - it should reject DAI formats other than
> CBS_CFM if that is the only configuration that's supported.
>
>> Refer to my description above,it's not possible to configure anything
>> for CPU DAI after a stream is opened ,that why we have to configure CPU
>> DAI before any stream is opened.
>
> This is normal (and generally trying would result in audio artifacts if
> you try), but normally there is at least some configuration that can be
> done before the stream actually starts running.
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