[alsa-devel] [PATCH 2/3] ASoC: DaVinci: pcm, rename variables in prep for ping/pong
avm at ti.com
Tue Sep 29 17:21:49 CEST 2009
DM355 uses MCBSP 1 instead of 0 as in DM644x. Do you think this will affect the channel swapping? Another thing is I was able to run aplay and arecord without Troy's patches, but seems like gstreamer still fails with his patches.
> -----Original Message-----
> From: davinci-linux-open-source-bounces+avm=ti.com at linux.davincidsp.com
> [mailto:davinci-linux-open-source-bounces+avm=ti.com at linux.davincidsp.com]
> On Behalf Of Nori, Sekhar
> Sent: Tuesday, September 29, 2009 6:46 AM
> To: Nori, Sekhar; Troy Kisky
> Cc: davinci-linux-open-source at linux.davincidsp.com; Mark Brown; alsa-
> devel at alsa-project.org
> Subject: RE: [alsa-devel] [PATCH 2/3] ASoC: DaVinci: pcm, rename variables
> in prep for ping/pong
> On Wed, Sep 09, 2009 at 17:38:42, Nori, Sekhar wrote:
> > On Fri, Sep 04, 2009 at 00:25:57, Troy Kisky wrote:
> > > Nori, Sekhar wrote:
> > > > On Thu, Sep 03, 2009 at 05:45:08, Troy Kisky wrote:
> > > >> Mark Brown wrote:
> > > >>> On Mon, Aug 31, 2009 at 04:31:44PM -0700, Troy Kisky wrote:
> > > > [...]
> > > >>> I'll probably also apply the first patch since nobody else seems
> to care
> > > >>> one way or another, but I would urge you to look at changing the
> > > >>> for the platform data to at most select the workaround only on
> CPUs that
> > > >>> have problems with channel swapping - it's going to cause
> confusion for
> > > >>> people to have it on by default.
> > > >>>
> > > >> I think the ones without a problem use davinci-mcasp instead of
> > > >> but share davinci-pcm. So, I don't know of any machines to exclude
> in davinci-i2s.
> > > >> But if someone else knows, speak up.
> > > >>
> > [...]
> > >
> > > >
> > > > Using EDMA acount=4 instead of 2 (32-bit transfers) did fix that
> issue on the
> > > > OSS drivers but I don't recall the problem morphing into an "always
> > > > swapped" case.
> > > >
> > > > Have you tested your patch (1/3) with DM644x EVM? If not, we can do
> that and
> > > > see if it leads to channels being always swapped on that hardware as
> > >
> > > Yes, I have tested with dm644x, not evm. I haven't tried to hear the
> channel swap,
> > > but I have no doubt that it is.
> > I finally got around to testing your patch 1/3 on DM6446 EVM.
> > Without your patch, channel swap is quite easy to reproduce using audio
> > loopback:
> > arecord -fcd | aplay -fcd
> > The audio source is a PC which speaker balance set to an extreme.
> > By starting and stopping this command repeatedly, you can see the audio
> > moving from one channel to the other.
> > Applying your patch fixes this issue.
> > Also, I did not notice any permanent channel swap. Used aplay to play
> > which was first left-only and then right-only. Plays the same way on a
> Linux PC.
> > I will test on couple of other platform using davinci-i2s (DM355 etc)
> > acking the patch.
> Even on the DM355 EVM this patch fixes the random channel swap on audio
> loopback 'arecord -fcd | aplay -fcd'.
> However, on playback, the channels do seem to be permanently swapped. This
> surely be blamed on this patch because, without it, the channels get
> Since this was not observed on DM6446 EVM, I have to see if the DM355 EVM
> hardware swaps the channels. I briefly compared the schematics of the two
> but nothing seems to be wrong there.
> Troy, do you have any theory yet on why your patch should permanently swap
> Anyway, the patch surely improves the situation on the EVMs, so, for patch
> of this series:
> Tested-by: Sekhar Nori <nsekhar at ti.com>
> [tested on DM6446 and DM355 EVMs]
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