Re: bugs in "ASoC: core - Optimise and refactor pcm_new() to pass only rtd"?

[James Hogan <james.hogan@imgtec.com>]

On 12/14/2011 01:34 PM, Mark Brown wrote:
> On Wed, Dec 14, 2011 at 12:43:50PM +0000, James Hogan wrote:
> 
>> I've bisected a problem with an out of tree set of asoc drivers down to commit
>> 552d1ef6b5a98d7b95959d5b139071e3c90cebf1 ("ASoC: core - Optimise and refactor
>> pcm_new() to pass only rtd"). By the looks of it this change was intended not 
>> to change the workings of the code, however the dai parameter of pcm_new used
>> to be passed codec_dai in soc_new_pcm() (initialised from rtd->codec_dai), but
>> each driver now sets it's dai to rtd->cpu_dai instead. This seems to make the
>> driver check the wrong dai's driver->capture.channels_min in the pcm_new
>> callback, which makes it dereference
>> pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream in the driver's
>> preallocate_dma_buffer() function which can be NULL. Is this a bug (in every
>> pcm asoc driver) that just happens not to have been noticed, or have I
>> misunderstood it?
> 
> Your drivers should never have beenn relying on this behaviour of the
> core - see changes in the pxa and fsl drivers which remove similar
> assumptions.  The CPU driver should be checking for the substream if
> it's looking to see if a particular substream is present, not peering
> inside the DAI for a random parameter.

Thanks Mark, we were basing our drivers on one of the other ones (I
think the atmel one, which still seems to do it as of v3.2-rc4).

Cheers
James