linux-kernel - Re: [PATCH 2/4] ASoC: sunxi: Add Allwinner A10 Digital Audio driver

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Date:	Thu, 9 Jun 2016 23:05:15 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
	Andrea Venturi <ennesimamail.av@...il.com>,
	Code Kipper <codekipper@...il.com>, gianfranco@...devices.com
Subject: Re: [PATCH 2/4] ASoC: sunxi: Add Allwinner A10 Digital Audio driver

Hi Mark,

On Thu, Jun 02, 2016 at 11:26:51AM +0100, Mark Brown wrote:
> > +static int sun4i_i2s_params_to_sr(struct snd_pcm_hw_params *params)
> > +{
> > +	switch (params_width(params)) {
> > +	case 16:
> > +		return 0;
> > +	}
> > +
> > +	return -EINVAL;
> > +}
> 
> The switch statement here and in the _wss() function look weird because
> they don't have default cases.  Since there's only one user of both
> functions it seems better to have the switch statements inline anyway.

I don't know, maybe it's just me, but I really find it cleaner that
way, and the compiler will probably inline it anyway. If you insist,
I'll change it though.


> > +	for (i = 0; sun4i_i2s_mclk_div[i].div; i++) {
> > +		const struct sun4i_i2s_clk_div *mdiv = sun4i_i2s_mclk_div + i;
> 
> Why not just write these as normal array lookups?

By normal, you mean using ARRAY_SIZE()?

> > +	/* Enable the first output line */
> > +	regmap_update_bits(i2s->regmap, SUN4I_I2S_CTRL_REG,
> > +			   SUN4I_I2S_CTRL_SDO_EN_MASK,
> > +			   SUN4I_I2S_CTRL_SDO_EN(0));
> > +
> > +	/* Enable the first two channels */
> > +	regmap_write(i2s->regmap, SUN4I_I2S_TX_CHAN_SEL_REG,
> > +		     SUN4I_I2S_TX_CHAN_SEL(2));
> > +
> > +	/* Map them to the two first samples coming in */
> > +	regmap_write(i2s->regmap, SUN4I_I2S_TX_CHAN_MAP_REG,
> > +		     SUN4I_I2S_TX_CHAN_MAP(0, 0) | SUN4I_I2S_TX_CHAN_MAP(1, 1));
> 
> We don't undo these if setup fails...  do them once on probe?

Yep

> > +static int sun4i_i2s_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
> > +{
> > +        struct sun4i_i2s *i2s = snd_soc_dai_get_drvdata(dai);
> > +	u32 val;
> 
> More tab/space damage, there seems to be quite a bit in the rest of the
> driver.

Indeed, sorry for that.

> > +static int sun4i_i2s_dai_probe(struct snd_soc_dai *dai)
> > +{
> > +	struct sun4i_i2s *i2s = snd_soc_dai_get_drvdata(dai);
> > +
> > +	/* Enable the whole hardware block */
> > +	regmap_write(i2s->regmap, SUN4I_I2S_CTRL_REG,
> > +		     SUN4I_I2S_CTRL_GL_EN);
> 
> Runtime PM?  It also seems like this is something that ought to be
> covered in the suspend and resume callbacks.

runtime_pm is supported, and uses the regmap cache to keep those
changes.

suspend and resume is not supported for that SoC yet, so I couldn't
test it properly (and isn't that redundant with runtime_pm?)

Thanks!
Maxime

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

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