[alsa-devel] [PATCH v2] tlv320aic3x: disable ADC/DAC while changing clock

Daniel Glöckner dg at emlix.com
Wed Apr 1 19:16:15 CEST 2009

On 04/01/2009 06:48 PM, Mark Brown wrote:
> On Wed, Apr 01, 2009 at 06:21:19PM +0200, Daniel Glöckner wrote:
>> It was my impression that it is up to the pcm part to install these
>> constraints as this is where SNDRV_PCM_INFO_JOINT_DUPLEX can be put into
>> the snd_pcm_hardware structure.
> JOINT_DUPLEX is just a hint to the application about how the card will
> behave - you still need to enforce the actual constraints you have in
> the driver.  In any case, the PCM driver shouldn't be setting that
> unless it has such a constraint itself since it should work with the
> widest possible range of systems.

Then there needs to be a way for codecs and machines to force this bit if
the PCM driver didn't set it.

IMHO joint duplex is a hack that works only by chance.
Constraints that depend on the configuration of the first stream on open of the
second stream are no longer valid when the first stream is closed.
It is also not possible to add constraints when the first stream has been opened
but not yet configured.


Dipl.-Math. Daniel Glöckner, emlix GmbH, http://www.emlix.com
Fon +49 551 30664-0, Fax -11, Bahnhofsallee 1b, 37081 Göttingen, Germany
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