Re: [PATCH v9 10/15] drm/bridge: analogix_dp: Add new API analogix_dp_finish_probe()

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

Hello Damon,

On Tue Feb 10, 2026 at 8:12 AM CET, Damon Ding wrote:
> Since the panel/bridge should logically be positioned behind the
> Analogix bridge in the display pipeline, it makes sense to handle
> the panel/bridge parsing on the Analogix side. Therefore, we add
> a new API analogix_dp_finish_probe(), which combines the panel/bridge
> parsing with component addition, to do it.
>
> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Tested-by: Heiko Stuebner <heiko@sntech.de> (on rk3588)

...

> @@ -1581,6 +1583,52 @@ struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp)
>  }
>  EXPORT_SYMBOL_GPL(analogix_dp_get_aux);
>
> +static int analogix_dp_aux_done_probing(struct drm_dp_aux *aux)
> +{
> +	struct analogix_dp_device *dp = to_dp(aux);
> +	struct analogix_dp_plat_data *plat_data = dp->plat_data;
> +	int port = plat_data->dev_type == EXYNOS_DP ? 0 : 1;
> +	int ret;
> +
> +	/*
> +	 * If drm_of_find_panel_or_bridge() returns -ENODEV, there may be no valid panel
> +	 * or bridge nodes. The driver should go on for the driver-free bridge or the DP
> +	 * mode applications.
> +	 */
> +	ret = drm_of_find_panel_or_bridge(dp->dev->of_node, port, 0,
> +					  &plat_data->panel, &plat_data->next_bridge);
> +	if (ret && ret != -ENODEV)
> +		return ret;
> +
> +	return component_add(dp->dev, plat_data->ops);
> +}
> +
> +int analogix_dp_finish_probe(struct analogix_dp_device *dp)
> +{
> +	int ret;
> +
> +	ret = devm_of_dp_aux_populate_bus(&dp->aux, analogix_dp_aux_done_probing);
> +	if (ret) {
> +		/*
> +		 * If devm_of_dp_aux_populate_bus() returns -ENODEV, the done_probing() will
> +		 * not be called because there are no EP devices. Then the callback function
> +		 * analogix_dp_aux_done_probing() will be called directly in order to support
> +		 * the other valid DT configurations.
> +		 *
> +		 * NOTE: The devm_of_dp_aux_populate_bus() is allowed to return -EPROBE_DEFER.

Uhm, if it is allowed to return -EPROBE_DEFER...

> +		 */
> +		if (ret != -ENODEV) {
> +			dev_err(dp->dev, "failed to populate aux bus\n");
> +			return ret;
> +		}

...then you shouldn't dev_err() when -EPROBE_DEFER is returned.

Either use dev_err_probe() (which would also simplify your code) or check
for if (ret != -ENODEV && ret != -EPROBE_DEFER).

> +
> +		return analogix_dp_aux_done_probing(&dp->aux);
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(analogix_dp_finish_probe);
> +
>  MODULE_AUTHOR("Jingoo Han <jg1.han@samsung.com>");
>  MODULE_DESCRIPTION("Analogix DP Core Driver");
>  MODULE_LICENSE("GPL v2");
> diff --git a/include/drm/bridge/analogix_dp.h b/include/drm/bridge/analogix_dp.h
> index 3428ffff24c5..bae969dec63a 100644
> --- a/include/drm/bridge/analogix_dp.h
> +++ b/include/drm/bridge/analogix_dp.h
> @@ -30,6 +30,7 @@ struct analogix_dp_plat_data {
>  	struct drm_bridge *next_bridge;
>  	struct drm_encoder *encoder;
>  	struct drm_connector *connector;
> +	const struct component_ops *ops;

Is adding a new stored field a good idea? Can it be instead passed as an
argument to analogix_dp_finish_probe()?

Note I don't have a strong opinion here, just the added struct field seems
overkill for being used just once.

> @@ -49,5 +50,6 @@ int analogix_dp_stop_crc(struct drm_connector *connector);
>
>  struct analogix_dp_plat_data *analogix_dp_aux_to_plat_data(struct drm_dp_aux *aux);
>  struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp);
> +int analogix_dp_finish_probe(struct analogix_dp_device *dp);
>
>  #endif /* _ANALOGIX_DP_H_ */

Luca

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