linux-kernel - Re: [PATCH v4 1/4] ASoC: rockchip: add support for i2s-tdm controller

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Message-ID: <20210915140502.GB12513@sirena.org.uk>
Date:   Wed, 15 Sep 2021 15:05:02 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Nicolas Frattaroli <frattaroli.nicolas@...il.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v4 1/4] ASoC: rockchip: add support for i2s-tdm controller

On Sat, Sep 04, 2021 at 01:15:33AM +0200, Nicolas Frattaroli wrote:

A few fairly small issues here, nothing too major:

> @@ -0,0 +1,1832 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ALSA SoC Audio Layer - Rockchip I2S/TDM Controller driver

Please write the entire comment as a C++ one so it looks more
itentional.  

> +	xfer_mask = (tx ? I2S_XFER_TXS_START : 0) |
> +		    (rx ? I2S_XFER_RXS_START : 0);
> +	xfer_val = (tx ? I2S_XFER_TXS_STOP : 0) |
> +		   (rx ? I2S_XFER_RXS_STOP : 0);

Please write normal conditional statements to improve legibility.

> +	spin_lock_irqsave(&i2s_tdm->lock, flags);
> +	if (on) {
> +		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
> +			rockchip_enable_tde(i2s_tdm->regmap);
> +		else
> +			rockchip_enable_rde(i2s_tdm->regmap);
> +
> +		if (atomic_inc_return(&i2s_tdm->refcount) == 1) {

Why do we need to use atomics here given that we're inside a spinlock?
Surely the spinlock is already providing adequate concurrency
protection.  I can't see any other points where we don't have the
spinlock already, and I'd be worried if we did.  This looks like it
could just be regular variables.

> +	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
> +	case SND_SOC_DAIFMT_CBS_CFS:

Please use the modern SOF_DAI_FMT_CBC_CFC defines.

> +	delta = (ppm < 0) ? -1 : 1;

Again, please write normal condiditional statements for legibility.

> +static int rockchip_i2s_tdm_clk_compensation_put(struct snd_kcontrol *kcontrol,
> +						 struct snd_ctl_elem_value *ucontrol)
> +{

> +	return ret;
> +}

This should return 1 if the value changed.

> +static int __maybe_unused rockchip_i2s_tdm_resume(struct device *dev)
> +{
> +	struct rk_i2s_tdm_dev *i2s_tdm = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0)
> +		return ret;
> +	ret = regcache_sync(i2s_tdm->regmap);
> +	pm_runtime_put(dev);

Runtime resume also does a regcache sync so why are we doing another one
here?

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