From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hogan Subject: Re: bugs in "ASoC: core - Optimise and refactor pcm_new() to pass only rtd"? Date: Wed, 14 Dec 2011 13:58:14 +0000 Message-ID: <4EE8AB76.6040202@imgtec.com> References: <4EE89A06.80101@imgtec.com> <20111214133448.GD25088@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20111214133448.GD25088@sirena.org.uk> Sender: linux-kernel-owner@vger.kernel.org To: Mark Brown Cc: Liam Girdwood , Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, linux-kernel , Neil List-Id: alsa-devel@alsa-project.org 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