linux-kernel - Re: [PATCH 2/2] ASoC: sunxi: add support for the on-chip codec on early Allwinner SoCs

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Date:	Thu, 17 Sep 2015 15:31:35 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	Emilio Lopez <emilio@...pez.com.ar>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-sunxi@...glegroups.com, alsa-devel@...a-project.org
Subject: Re: [PATCH 2/2] ASoC: sunxi: add support for the on-chip codec on
 early Allwinner SoCs

Hi Mark,

On Wed, Sep 16, 2015 at 08:16:12PM +0100, Mark Brown wrote:
> On Sat, Sep 12, 2015 at 03:26:24PM +0200, Maxime Ripard wrote:
> 
> This looks pretty good, there's a few minor things below but I'll apply
> anyway - please send followup patches fixing these.

Sure, I will. Thanks!

> 
> > +	if (clk_set_rate(scodec->clk_module, clk_freq))
> > +		return -EINVAL;
> 
> Better to pass back the error code here rather than silently discard it
> (it might have more information).

Yep.

> 
> > +static struct snd_soc_dai_driver sun4i_codec_dai = {
> > +	.name	= "Codec",
> > +	.ops	= &sun4i_codec_dai_ops,
> > +	.playback = {
> > +		.stream_name	= "Codec Playback",
> > +		.channels_min	= 1,
> > +		.channels_max	= 2,
> > +		.rate_min	= 8000,
> > +		.rate_max	= 192000,
> > +		.rates		= SNDRV_PCM_RATE_8000_48000 |
> > +				  SNDRV_PCM_RATE_96000 |
> > +				  SNDRV_PCM_RATE_192000 |
> > +				  SNDRV_PCM_RATE_KNOT,
> 
> No need to specify both explicit rates and _KNOT, _KNOT covers
> everything.

Ack.

> > +		.formats	= SNDRV_PCM_FMTBIT_S16_LE |
> > +				  SNDRV_PCM_FMTBIT_S32_LE,
> > +		.sig_bits	= 24,
> 
> So presumably also S24_LE (ie, 24 bits packed into a 32 bit word)?

Hmm, probably yes, I'll test that.

> > +	/* Enable the bus clock */
> > +	if (clk_prepare_enable(scodec->clk_apb)) {
> > +		dev_err(&pdev->dev, "Failed to enable the APB clock\n");
> > +		return -EINVAL;
> > +	}
> 
> Ideally we'd have runtime power management to disable the clocks when
> idle.

We don't really have any kind of power management support currently,
but adding runtime pm everywhere is definitely on the todo list. It
might not happen before a while though.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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