linux-kernel - Re: [PATCH v2 2/2] phy: intel-lgm-emmc: Add support for eMMC PHY

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Date:   Tue, 20 Aug 2019 16:56:02 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     "Ramuthevar,Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@...ux.intel.com>
Cc:     kishon@...com, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, cheol.yong.kim@...el.com,
        qi-ming.wu@...el.com, peter.harliman.liem@...el.com
Subject: Re: [PATCH v2 2/2] phy: intel-lgm-emmc: Add support for eMMC PHY

On Tue, Aug 20, 2019 at 06:31:33PM +0800, Ramuthevar,Vadivel MuruganX wrote:
> From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@...ux.intel.com>
> 
> Add support for eMMC PHY on Intel's Lightning Mountain SoC.

Thanks for an update.
Looks better though several minor comments below.


> +/* eMMC phy register definitions */
> +#define EMMC_PHYCTRL0_REG	0xa8
> +#define DR_TY_MASK		GENMASK(30, 28)

> +#define DR_TY_50OHM(x)		((~(x) << 28) & DR_TY_MASK)

For consistency it should be

#define DR_TY_SHIFT(x)		(((x) << 28) & DR_TY_MASK)

with explanation about 50 Ohm in the code below.

> +#define OTAPDLYENA		BIT(14)
> +#define OTAPDLYSEL_MASK		GENMASK(13, 10)
> +#define OTAPDLYSEL_SHIFT(x)	(((x) << 10) & OTAPDLYSEL_MASK)
> +
> +#define EMMC_PHYCTRL1_REG	0xac
> +#define PDB_MASK		BIT(0)
> +#define ENDLL_MASK		BIT(7)

> +#define ENDLL_VAL		BIT(7)

Again, inconsistency here,

#define ENDLL_SHIFT(x)		(((x) << 7) & ENDLL_MASK)

> +#define EMMC_PHYCTRL2_REG	0xb0
> +#define FRQSEL_25M		0
> +#define FRQSEL_150M		3
> +#define FRQSEL_MASK		GENMASK(24, 22)

> +#define FRQSEL_SHIFT(x)		((x) << 22)

And here

#define FRQSEL_SHIFT(x)		(((x) << 22) & FRQSEL_MASK)

> +	/*
> +	 * According to the user manual, calpad calibration
> +	 * cycle takes more than 2us without the minimal recommended
> +	 * value, so we may need a little margin here
> +	 */

> +	usleep_range(3, 6);

Actually for this low values it's recommended to use udelay() disregard to
context.

	udelay(5);

> +	regmap_update_bits(priv->syscfg, EMMC_PHYCTRL1_REG, PDB_MASK, 1);

1 looks like a magic that has to be changed in the same way as for the rest, i.e.

#define PDB_SHIFT(x)	(((x) << 0) & PDB_MASK)

	..., PDB_MASK, PDB_SHIFT(1)...

> +static int intel_emmc_phy_power_on(struct phy *phy)
> +{
> +	struct intel_emmc_phy *priv = phy_get_drvdata(phy);
> +	int ret;
> +
> +	/* Drive impedance: 50 Ohm */

Nice, you have already a comment here. Just use DR_TY_SHIFT(1)

> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL0_REG, DR_TY_MASK,
> +				 DR_TY_50OHM(1));

> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL0_REG, OTAPDLYENA,
> +				 0x0);

0x0 -> 0

> +static int intel_emmc_phy_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct intel_emmc_phy *priv;
> +	struct phy *generic_phy;
> +	struct phy_provider *phy_provider;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	/* Get eMMC phy (accessed via chiptop) regmap */

> +	priv->syscfg = syscon_regmap_lookup_by_phandle(dev->of_node,
> +						       "intel,syscon");

Perhaps

	struct device_node *np = dev->of_node;
	...
	priv->syscfg = syscon_regmap_lookup_by_phandle(np, "intel,syscon");

> +	generic_phy = devm_phy_create(dev, dev->of_node, &ops);

And here.

-- 
With Best Regards,
Andy Shevchenko