[alsa-devel] [PATCH v3 4/5] ASoC: tda998x: adjust the audio hw parameters from EDID
lars at metafoo.de
Wed Feb 5 04:19:22 EST 2014
On 02/05/2014 10:11 AM, Jean-Francois Moine wrote:
> On Tue, 4 Feb 2014 18:06:25 +0000
> Mark Brown <broonie at kernel.org> wrote:
>> On Mon, Jan 27, 2014 at 09:48:54AM +0100, Jean-Francois Moine wrote:
>>> + /* change the snd_soc_pcm_stream values of the driver */
>>> + stream->rates = rate_mask;
>>> + stream->channels_max = max_channels;
>>> + stream->formats = formats;
>>> + /* copy the DAI driver to a writable area */
>>> + dai_drv = devm_kzalloc(&pdev->dev, sizeof(tda998x_dai), GFP_KERNEL);
>>> + if (!dai_drv)
>>> + return -ENOMEM;
>>> + memcpy(dai_drv, tda998x_dai, sizeof(tda998x_dai));
>> The code should be doing this by setting constraints based on the
>> current setup rather than by editing the data structure - the expecation
>> is very much that the data won't change so this prevents surprises with
>> future work on the core.
> As it is done in the soc core, in soc_pcm_open(), the runtime hw_params
> are initialized after the call to the CODEC startup, and the next CODEC
> event is hw_params() when the user has already chosen all the parameters.
> So, in the CODEC, I don't see how I could update the parameters
> dictated by the EDID otherwise in changing the DAI driver parameters.
The startup function is the right place. But instead of modifying the DAI
use snd_pcm_hw_constraint_mask64(), snd_pcm_hw_constraint_list(), etc. to
setup the additional constraints that come from the EDID.
Bonus points for making this a generic helper function that takes a runtime
and a EDID and then applies the EDID constraints on the runtime.
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