Re: [PATCH v4 08/12] drm/mediatek: mtk_dp: Add support for PHY from devicetree

[CK Hu (胡俊光)]

On Thu, 2026-07-09 at 13:31 +0200, AngeloGioacchino Del Regno wrote:
> Add support for specifying `phys` in devicetree to pass handle
> to the DisplayPort PHY.
> 
> In order to retain compatibility with older devicetrees, check if
> `phys` was specified: if not, initialize the regmap_mmio with the
> legacy configuration and register the mediatek-dp-phy platform
> device from this driver, and get the PHY calibration data.

Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>

> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 50 ++++++++++++++++++++++++++-----
>  1 file changed, 43 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
> index 383c8e66b527..e2a6001fc0cc 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -426,6 +426,15 @@ static const struct regmap_config mtk_dp_regmap_legacy_config = {
>  	.name = "mtk-dp-registers",
>  };
>  
> +static const struct regmap_config mtk_dp_regmap_config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.max_register = SEC_OFFSET + 0x90,
> +	.name = "mtk-dp-registers",
> +};
> +
> +
>  static struct mtk_dp *mtk_dp_from_bridge(struct drm_bridge *b)
>  {
>  	return container_of(b, struct mtk_dp, bridge);
> @@ -1287,7 +1296,13 @@ static int mtk_dp_phy_configure(struct mtk_dp *mtk_dp,
>  	if (ret)
>  		return ret;
>  
> -	mtk_dp_set_calibration_data(mtk_dp);
> +	/*
> +	 * For legacy, deprecated strategy, set partial PHY calibration here.
> +	 * New-style will set all PHY calibrations with phy ops instead.
> +	 */
> +	if (mtk_dp->phy_dev)
> +		mtk_dp_set_calibration_data(mtk_dp);
> +
>  	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
>  			   DP_PWR_STATE_BANDGAP_TPLL_LANE, DP_PWR_STATE_MASK);
>  
> @@ -2120,8 +2135,9 @@ static int mtk_dp_wait_hpd_asserted(struct drm_dp_aux *mtk_aux, unsigned long wa
>  static int mtk_dp_dt_parse(struct mtk_dp *mtk_dp,
>  			   struct platform_device *pdev)
>  {
> -	struct device_node *endpoint;
> +	const struct regmap_config *regmap_cfg;
>  	struct device *dev = &pdev->dev;
> +	struct device_node *endpoint;
>  	int ret;
>  	void __iomem *base;
>  	u32 linkrate;
> @@ -2131,7 +2147,12 @@ static int mtk_dp_dt_parse(struct mtk_dp *mtk_dp,
>  	if (IS_ERR(base))
>  		return PTR_ERR(base);
>  
> -	mtk_dp->regs = devm_regmap_init_mmio(dev, base, &mtk_dp_regmap_legacy_config);
> +	if (!mtk_dp->legacy_regoff)
> +		regmap_cfg = &mtk_dp_regmap_config;
> +	else
> +		regmap_cfg = &mtk_dp_regmap_legacy_config;
> +
> +	mtk_dp->regs = devm_regmap_init_mmio(dev, base, regmap_cfg);
>  	if (IS_ERR(mtk_dp->regs))
>  		return PTR_ERR(mtk_dp->regs);
>  
> @@ -2754,6 +2775,7 @@ static int mtk_dp_register_phy(struct mtk_dp *mtk_dp)
>  		return dev_err_probe(dev, ret,
>  				     "Failed to add phy unregister devm action");
>  
> +	/* PHY calibration data is in mtk_dp only for legacy devicetree */
>  	mtk_dp_get_calibration_data(mtk_dp);
>  
>  	mtk_dp->phy = devm_phy_get(&mtk_dp->phy_dev->dev, "dp");
> @@ -2804,7 +2826,12 @@ static int mtk_dp_probe(struct platform_device *pdev)
>  
>  	mtk_dp->dev = dev;
>  	mtk_dp->data = (struct mtk_dp_data *)of_device_get_match_data(dev);
> -	mtk_dp->legacy_regoff = MTK_DP_TOP_OFFSET_LEGACY;
> +
> +	/* Prefer PHY from devicetree - if not found, this is legacy */
> +	if (of_property_present(dev->of_node, "phys"))
> +		mtk_dp->legacy_regoff = 0;
> +	else
> +		mtk_dp->legacy_regoff = MTK_DP_TOP_OFFSET_LEGACY;
>  
>  	ret = mtk_dp_dt_parse(mtk_dp, pdev);
>  	if (ret)
> @@ -2855,9 +2882,18 @@ static int mtk_dp_probe(struct platform_device *pdev)
>  					     "Failed to register audio driver\n");
>  	}
>  
> -	ret = mtk_dp_register_phy(mtk_dp);
> -	if (ret)
> -		return ret;
> +	if (!mtk_dp->legacy_regoff) {
> +		mtk_dp->phy = devm_phy_get(dev, NULL);
> +		if (IS_ERR(mtk_dp->phy))
> +			return dev_err_probe(dev, PTR_ERR(mtk_dp->phy),
> +					     "Failed to get phy\n");
> +
> +		mtk_dp->phy_dev = NULL;
> +	} else {
> +		ret = mtk_dp_register_phy(mtk_dp);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	mtk_dp->bridge.of_node = dev->of_node;
>  	mtk_dp->bridge.type = mtk_dp->data->bridge_type;