linux-kernel - Re: [PATCH v3 4/5] ASoC: tda998x: adjust the audio hw parameters from EDID

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Message-ID: <20140205101134.4591e5c3@armhf>
Date:	Wed, 5 Feb 2014 10:11:34 +0100
From:	Jean-Francois Moine <moinejf@...e.fr>
To:	Mark Brown <broonie@...nel.org>
Cc:	alsa-devel@...a-project.org, Dave Airlie <airlied@...il.com>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Rob Clark <robdclark@...il.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>
Subject: Re: [PATCH v3 4/5] ASoC: tda998x: adjust the audio hw parameters
 from EDID

On Tue, 4 Feb 2014 18:06:25 +0000
Mark Brown <broonie@...nel.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.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/
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