linux-kernel - Re: [PATCH] ASoC: MAX9860: new driver

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Date:	Wed, 11 May 2016 16:29:50 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Peter Rosin <peda@...ntia.se>
Cc:	linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH] ASoC: MAX9860: new driver

On Tue, May 10, 2016 at 05:06:37PM +0200, Peter Rosin wrote:

> +		if (master) {
> +			switch (max9860->pclk_rate) {
> +			case 12000000:
> +				sysclk = MAX9860_FREQ_12MHZ;
> +				break;
> +			case 13000000:
> +				sysclk = MAX9860_FREQ_13MHZ;
> +				break;
> +			case 19200000:
> +				sysclk = MAX9860_FREQ_19_2MHZ;
> +				break;
> +			}

What if we have another PCLK rate?

> +#ifdef CONFIG_PM
> +static int max9860_suspend(struct device *dev)
> +{
> +	struct max9860_priv *max9860 = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = regmap_update_bits(max9860->regmap, MAX9860_SYSCLK,
> +				 MAX9860_PSCLK, MAX9860_PSCLK_OFF);
> +	if (ret) {
> +		dev_err(dev, "Failed to disable clock: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int max9860_resume(struct device *dev)
> +{
> +	struct max9860_priv *max9860 = dev_get_drvdata(dev);
> +	int ret;
> +
> +	regcache_cache_only(max9860->regmap, false);
> +	ret = regcache_sync(max9860->regmap);

We didn't go into cache only mode on suspend?  I'd also expect to see
the regulators disabled over suspend and some system PM ops.

> +static int max9860_mclk_rate(struct device *dev, unsigned long *mclk_rate)
> +{
> +	struct clk *mclk = clk_get(dev, "mclk");

Request resources on probe, not at some random point in driver
execution.  That will mean probe deferral works properly and that we
don't get broken devices instantiated in userspace.

> +	ret = clk_prepare_enable(mclk);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable MCLK: %d\n", ret);
> +		clk_put(mclk);
> +		return ret;
> +	}
> +
> +	*mclk_rate = clk_get_rate(mclk);
> +
> +	clk_disable_unprepare(mclk);

This is definitely confused too.  Enabling the clock to read the
programmed frequency is at best odd, and obviously if we do get the rate
this will ensure that MCLK is disabled which probably isn't ideal.

> +err_pm:
> +	pm_runtime_disable(dev);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(max9860_probe);

I've no idea why this is exported...

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