Re: [PATCH v3] drm/bridge: analogix_dp: use devm_phy_optional_get() for the DP PHY

["Luca Ceresoli" <luca.ceresoli@bootlin.com>]

Hello,

On Tue Nov 10, 2026 at 3:37 AM CET, Jun Yan wrote:
> The DP PHY is optional: the Rockchip RK3399 eDP controller (used as the
> internal eDP port) has no separate PHY device and relies on its built-in
> PHY, which is programmed directly through the GRF registers, so its DT
> node carries no "phys"/"phy-names" property.
>
> Requesting the PHY with devm_phy_get() therefore returns -ENODEV (or
> -ENOSYS when CONFIG_GENERIC_PHY is disabled) and the driver logs a
> misleading "no DP phy configured" error at probe time before falling back
> to a NULL phy.
>
> Use devm_phy_optional_get() instead, which returns NULL when the PHY is
> absent and otherwise behaves identically, and drop the manual -ENODEV/
> -ENOSYS handling. This also removes the spurious error message.
>
> Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>
> Reviewed-by: Damon Ding <damon.ding@rock-chips.com>
> ---
> Changes in v3:
>   - Add missing changelog entries and reference links
>   - Link to v2: https://lore.kernel.org/dri-devel/20261013134659.335829-1-jerrysteve1101@gmail.com/
>
> Changes in v2:
>   - Added comments to explain the changes made.
>   - Link to v1: https://lore.kernel.org/dri-devel/20260924020417.868588-1-jerrysteve1101@gmail.com/
>
>  .../drm/bridge/analogix/analogix_dp_core.c    | 22 ++++++-------------
>  1 file changed, 7 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 6df6963740d2..637b1bff0f6c 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -1426,21 +1426,13 @@ analogix_dp_probe(struct device *dev, struct analogix_dp_plat_data *plat_data)
>  	if (ret)
>  		return ERR_PTR(ret);
>
> -	dp->phy = devm_phy_get(dp->dev, "dp");
> -	if (IS_ERR(dp->phy)) {
> -		dev_err(dp->dev, "no DP phy configured\n");
> -		ret = PTR_ERR(dp->phy);
> -		if (ret) {
> -			/*
> -			 * phy itself is not enabled, so we can move forward
> -			 * assigning NULL to phy pointer.
> -			 */
> -			if (ret == -ENOSYS || ret == -ENODEV)
> -				dp->phy = NULL;
> -			else
> -				return ERR_PTR(ret);
> -		}
> -	}
> +	/*
> +	 * RK3288/RK3399 use Analogix DP controller built-in PHY,
> +	 * no extra PHY configuration is required.
> +	 */
> +	dp->phy = devm_phy_optional_get(dp->dev, "dp");
> +	if (IS_ERR(dp->phy))
> +		return ERR_CAST(dp->phy);

The original code ignbores -ENOSYS, devm_phy_optional_get() does not. So,
either -ENOSYS was just impossible, or this patch potentially changes the
behaviour.

Can you elaborate on that?

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com