Re: [PATCH v5 7/9] drm/bridge_connector: hook drm_atomic_helper_connector_hdmi_update_edid()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sun, 01 Dec 2024, Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote:
> Extend drm_bridge_connector code to read the EDID and use it to update
> connector status if the bridge chain implements HDMI bridge. Performing
> it from the generic location minimizes individual bridge's code and
> enforces standard behaviour from all corresponding drivers.
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/gpu/drm/display/drm_bridge_connector.c | 67 ++++++++++++++++++++------
>  1 file changed, 53 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
> index 12ab9f14cc8a8672478ae2804c9a68d766d88ea5..71ae3b2c9049016d1cc0d39a787f6461633efd53 100644
> --- a/drivers/gpu/drm/display/drm_bridge_connector.c
> +++ b/drivers/gpu/drm/display/drm_bridge_connector.c
> @@ -17,6 +17,7 @@
>  #include <drm/drm_edid.h>
>  #include <drm/drm_managed.h>
>  #include <drm/drm_modeset_helper_vtables.h>
> +#include <drm/drm_print.h>
>  #include <drm/drm_probe_helper.h>
>  #include <drm/display/drm_hdmi_state_helper.h>
>  
> @@ -175,17 +176,55 @@ static void drm_bridge_connector_disable_hpd(struct drm_connector *connector)
>   * Bridge Connector Functions
>   */
>  
> +static const struct drm_edid *
> +drm_bridge_connector_read_edid(struct drm_connector *connector,
> +			       enum drm_connector_status status)
> +{
> +	struct drm_bridge_connector *bridge_connector =
> +		to_drm_bridge_connector(connector);
> +	const struct drm_edid *drm_edid;
> +	struct drm_bridge *bridge;
> +
> +	bridge = bridge_connector->bridge_edid;
> +	if (!bridge)
> +		return NULL;
> +
> +	if (status != connector_status_connected)
> +		return NULL;
> +
> +	drm_edid = drm_bridge_edid_read(bridge, connector);
> +	if (!drm_edid_valid(drm_edid)) {

What's the case this check is for?

My preference would be that bridge->funcs->edid_read() uses
drm_edid_read*() family of functions that do the checks and return the
EDID.

There are some cases that just allocate a blob and return it. Would be
nice if they could be converted, but in the mean time could use
drm_edid_valid() right there. Additional validity checks are redundant.

BR,
Jani.


> +		drm_edid_free(drm_edid);
> +		return NULL;
> +	}
> +
> +	return drm_edid;
> +}
> +
>  static enum drm_connector_status
>  drm_bridge_connector_detect(struct drm_connector *connector, bool force)
>  {
>  	struct drm_bridge_connector *bridge_connector =
>  		to_drm_bridge_connector(connector);
>  	struct drm_bridge *detect = bridge_connector->bridge_detect;
> +	struct drm_bridge *hdmi = bridge_connector->bridge_hdmi;
>  	enum drm_connector_status status;
>  
>  	if (detect) {
>  		status = detect->funcs->detect(detect);
>  
> +		if (hdmi) {
> +			const struct drm_edid *drm_edid;
> +			int ret;
> +
> +			drm_edid = drm_bridge_connector_read_edid(connector, status);
> +			ret = drm_atomic_helper_connector_hdmi_update_edid(connector, drm_edid);
> +			if (ret)
> +				drm_warn(connector->dev, "updating EDID failed with %d\n", ret);
> +
> +			drm_edid_free(drm_edid);
> +		}
> +
>  		drm_bridge_connector_hpd_notify(connector, status);
>  	} else {
>  		switch (connector->connector_type) {
> @@ -246,29 +285,29 @@ static const struct drm_connector_funcs drm_bridge_connector_funcs = {
>  static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
>  					       struct drm_bridge *bridge)
>  {
> +	struct drm_bridge_connector *bridge_connector =
> +		to_drm_bridge_connector(connector);
> +	struct drm_bridge *hdmi = bridge_connector->bridge_hdmi;
>  	enum drm_connector_status status;
>  	const struct drm_edid *drm_edid;
> -	int n;
>  
>  	status = drm_bridge_connector_detect(connector, false);
>  	if (status != connector_status_connected)
> -		goto no_edid;
> +		return 0;
>  
> -	drm_edid = drm_bridge_edid_read(bridge, connector);
> -	if (!drm_edid_valid(drm_edid)) {
> +	/* In HDMI setup the EDID has been read and handled as a part of .detect() */
> +	if (!hdmi) {
> +		drm_edid = drm_bridge_connector_read_edid(connector, status);
> +		if (!drm_edid) {
> +			drm_edid_connector_update(connector, NULL);
> +			return 0;
> +		}
> +
> +		drm_edid_connector_update(connector, drm_edid);
>  		drm_edid_free(drm_edid);
> -		goto no_edid;
>  	}
>  
> -	drm_edid_connector_update(connector, drm_edid);
> -	n = drm_edid_connector_add_modes(connector);
> -
> -	drm_edid_free(drm_edid);
> -	return n;
> -
> -no_edid:
> -	drm_edid_connector_update(connector, NULL);
> -	return 0;
> +	return drm_edid_connector_add_modes(connector);
>  }
>  
>  static int drm_bridge_connector_get_modes(struct drm_connector *connector)

-- 
Jani Nikula, Intel