linux-kernel - Re: [PATCH 1/2] ASoC: fsl_xcvr: Add XCVR ASoC CPU DAI driver

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Date:   Thu, 17 Sep 2020 00:14:31 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     "Viorel Suman (OSS)" <viorel.suman@....nxp.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, Timur Tabi <timur@...nel.org>,
        Xiubo Li <Xiubo.Lee@...il.com>,
        Fabio Estevam <festevam@...il.com>,
        Shengjiu Wang <shengjiu.wang@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Matthias Schiffer <matthias.schiffer@...tq-group.com>,
        Cosmin-Gabriel Samoila <cosmin.samoila@....com>,
        Viorel Suman <viorel.suman@....com>,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        NXP Linux Team <linux-imx@....com>,
        Viorel Suman <viorel.suman@...il.com>
Subject: Re: [PATCH 1/2] ASoC: fsl_xcvr: Add XCVR ASoC CPU DAI driver

Hi Viorel,

It looks pretty clean to me, though some small comments inline.

On Wed, Sep 16, 2020 at 12:17:55PM +0300, Viorel Suman (OSS) wrote:
> From: Viorel Suman <viorel.suman@....com>
> 
> XCVR (Audio Transceiver) is a on-chip functional module found
> on i.MX8MP. It support HDMI2.1 eARC, HDMI1.4 ARC and SPDIF.
> 
> Signed-off-by: Viorel Suman <viorel.suman@....com>

> +static const u32 fsl_xcvr_earc_channels[] = { 1, 2, 8, 16, 32, }; /* one bit 6, 12 ? */

What's the meaning of the comments?

> +static const int fsl_xcvr_phy_arc_cfg[] = {
> +	FSL_XCVR_PHY_CTRL_ARC_MODE_SE_EN, FSL_XCVR_PHY_CTRL_ARC_MODE_CM_EN,
> +};

Nit: better be u32 vs. int?

> +/** phy: true => phy, false => pll */
> +static int fsl_xcvr_ai_write(struct fsl_xcvr *xcvr, u8 reg, u32 data, bool phy)
> +{
> +	u32 val, idx, tidx;
> +
> +	idx  = BIT(phy ? 26 : 24);
> +	tidx = BIT(phy ? 27 : 25);
> +
> +	regmap_write(xcvr->regmap, FSL_XCVR_PHY_AI_CTRL_CLR, 0xFF);
> +	regmap_write(xcvr->regmap, FSL_XCVR_PHY_AI_CTRL_SET, reg);
> +	regmap_write(xcvr->regmap, FSL_XCVR_PHY_AI_WDATA, data);
> +	regmap_write(xcvr->regmap, FSL_XCVR_PHY_AI_CTRL_TOG, idx);
> +
> +	do {
> +		regmap_read(xcvr->regmap, FSL_XCVR_PHY_AI_CTRL, &val);
> +	} while ((val & idx) != ((val & tidx) >> 1));

Might regmap_read_poll_timeout() be better? And it seems to poll
intentionally with no sleep nor timeout -- would be nice to have
a line of comments to explain why.

> > +static int fsl_xcvr_runtime_resume(struct device *dev)
> +{
> +	struct fsl_xcvr *xcvr = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(xcvr->ipg_clk);
> +	if (ret) {
> +		dev_err(dev, "failed to start IPG clock.\n");
> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(xcvr->pll_ipg_clk);
> +	if (ret) {
> +		dev_err(dev, "failed to start PLL IPG clock.\n");

Should it disable ipg_clk?

> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(xcvr->phy_clk);
> +	if (ret) {
> +		dev_err(dev, "failed to start PHY clock: %d\n", ret);
> +		clk_disable_unprepare(xcvr->ipg_clk);

Should it disable pll_ipg_clk?

> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(xcvr->spba_clk);
> +	if (ret) {
> +		dev_err(dev, "failed to start SPBA clock.\n");
> +		clk_disable_unprepare(xcvr->phy_clk);
> +		clk_disable_unprepare(xcvr->ipg_clk);

Ditto

> +		return ret;
> +	}
> +
> +	regcache_cache_only(xcvr->regmap, false);
> +	regcache_mark_dirty(xcvr->regmap);
> +	ret = regcache_sync(xcvr->regmap);
> +
> +	if (ret) {
> +		dev_err(dev, "failed to sync regcache.\n");
> +		return ret;

What about those clocks? Probably better to have some error-out
labels at the end of the function?

> +	}
> +
> +	reset_control_assert(xcvr->reset);
> +	reset_control_deassert(xcvr->reset);
> +
> +	ret = fsl_xcvr_load_firmware(xcvr);
> +	if (ret) {
> +		dev_err(dev, "failed to load firmware.\n");
> +		return ret;

Ditto

> +	}
> +
> +	/* Release M0+ reset */
> +	ret = regmap_update_bits(xcvr->regmap, FSL_XCVR_EXT_CTRL,
> +				 FSL_XCVR_EXT_CTRL_CORE_RESET, 0);
> +	if (ret < 0) {
> +		dev_err(dev, "M0+ core release failed: %d\n", ret);
> +		return ret;

Ditto

> +	}
> +	mdelay(50);

Any reason to use mdelay over msleep for a 50ms wait? May add a
line of comments if mdelay is a must?