Re: [PATCH v3 08/12] phy: phy-mtk-dp: Add support for digital and analog calibration

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

New issues:
- [Medium] Unconditional `dev_err` logging in `mtk_dp_phy_get_one_cal_para()` causes log spam for expected fallback cases (missing eFuses) and probe deferrals.

Pre-existing issues:
- [High] Unconditional dereference of `dev->platform_data` in legacy probe before validating it is non-NULL.
--

--- Patch [8]: [PATCH v3 08/12] phy: phy-mtk-dp: Add support for digital and analog calibration ---
commit 637b7b00f751ea110c4b395e4e951eecc2ab535e
Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

phy: phy-mtk-dp: Add support for digital and analog calibration

Add support for reading the calibration values from eFuse: if
present, write those - otherwise, rely on the defaults from
SoC-specific data. This also adds support for writing the calibration
values for the analog part of the PHY.

> diff --git a/drivers/phy/mediatek/phy-mtk-dp.c b/drivers/phy/mediatek/phy-mtk-dp.c
> index c87e9fa710a40..f59a415b401c5 100644
> --- a/drivers/phy/mediatek/phy-mtk-dp.c
> +++ b/drivers/phy/mediatek/phy-mtk-dp.c
[ ... ]
> @@ -422,6 +541,111 @@ static const struct phy_ops mtk_dp_phy_dev_ops = {
>  	.owner = THIS_MODULE,
>  };
>  
> +static void mtk_dp_phy_get_default_cal_data(struct mtk_dp_phy *dp_phy)
[ ... ]
> +static int mtk_dp_phy_get_one_cal_para(struct device *dev, const char *name, u8 max_val)
> +{
> +	u8 buf_byte;
> +	u16 buf;
> +	int ret;
> +
> +	/*
> +	 * All of the calibrations are always max 8 bits long, but some may
> +	 * be split between two different 8-bits cells: handle this corner
> +	 * case by retrying reading as u16.
> +	 */
> +	ret = nvmem_cell_read_u8(dev, name, &buf_byte);
> +	if (ret)
> +		ret = nvmem_cell_read_u16(dev, name, &buf);
> +	else
> +		buf = buf_byte;
> +
> +	if (ret) {
> +		dev_err(dev, "Cannot get calibration data for %s: %d\n", name, ret);
> +		return ret;
> +	};

[Severity: Medium]
Will this unconditionally log an error when calibration data is intentionally
omitted or when the nvmem provider returns -EPROBE_DEFER?

If the calibration data is missing, nvmem_cell_read_u8() returns -ENOENT,
which is later handled gracefully by the caller by falling back to defaults.
However, printing dev_err() here will cause log spam and false-positive
errors in dmesg. Could this be silenced for -ENOENT and -EPROBE_DEFER cases?

> +
> +	if (buf == 0) {
[ ... ]
> @@ -453,6 +677,13 @@ static int mtk_dp_phy_legacy_probe(struct platform_device *pdev, struct mtk_dp_p
>  				     "Failed to create DP PHY\n");
>  
>  	phy_set_drvdata(phy, dp_phy);

[Severity: High]
This is a pre-existing issue, but earlier in mtk_dp_phy_legacy_probe(),
does the code unconditionally dereference dev->platform_data before checking
if it is NULL?

drivers/phy/mediatek/phy-mtk-dp.c:mtk_dp_phy_legacy_probe() {
    ...
	dp_phy->regmap = *(struct regmap **)dev->platform_data;
	if (!dp_phy->regmap)
		return dev_err_probe(dev, -EINVAL, "No platform data available\n");
    ...
}

If the platform device is instantiated without platform data,
*(struct regmap **)NULL results in an immediate kernel panic, making the
subsequent check dead code.

> +
> +	/*
> +	 * Set default calibration data before exposing the PHY.
> +	 * For legacy probe, mtk_dp will set calibrations from eFuse, if found.
> +	 */
> +	mtk_dp_phy_get_default_cal_data(dp_phy);
> +
>  	ret = phy_create_lookup(phy, "dp", dev_name(dev));
>  	if (ret)
>  		return ret;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260707154245.198361-1-angelogioacchino.delregno@collabora.com?part=8

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