Re: [PATCH v2 1/3] Revert "drm/display: bridge_connector: get/put the stored bridges"

[Louis Chauvet <louis.chauvet@bootlin.com>]

Le 17/10/2025 à 18:15, Luca Ceresoli a écrit :
> This reverts commit 2be300f9a0b6f6b0ae2a90be97e558ec0535be54.
> 
> The commit being reverted moved all the bridge_connector->bridge_*
> assignments to just before the final successful return in order to handle
> the bridge refcounting in a clean way.
> 
> This introduced a bug, because a bit before the successful return
> drmm_connector_hdmi_cec_register() is called, which calls funcs->init()
> which is drm_bridge_connector_hdmi_cec_init() which needs
> bridge_connector->bridge_hdmi_cec to be set.
> 
> The reported bug may be fixed in a relatively simple way, but other similar
> patterns are potentially present, so just revert the offending commit. A
> different approach will be implemented.
> 
> Fixes: 2be300f9a0b6 ("drm/display: bridge_connector: get/put the stored bridges")
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Closes: https://lore.kernel.org/all/336fbfdd-c424-490e-b5d1-8ee84043dc80@samsung.com/
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Closes: https://lore.kernel.org/r/CA+G9fYuKHp3QgPKjgFY3TfkDdh5Vf=Ae5pCW+eU41Bu=D7th2g@mail.gmail.com
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>

> ---
> 
> Changes in v2: none
> ---
>   drivers/gpu/drm/display/drm_bridge_connector.c | 114 ++++++++-----------------
>   1 file changed, 36 insertions(+), 78 deletions(-)
> 
> diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
> index 7b18be3ff9a32b362468351835bdab43c3f524f1..a5bdd6c1064399ece6b19560f145b877c9e0680e 100644
> --- a/drivers/gpu/drm/display/drm_bridge_connector.c
> +++ b/drivers/gpu/drm/display/drm_bridge_connector.c
> @@ -618,20 +618,6 @@ static const struct drm_connector_hdmi_cec_funcs drm_bridge_connector_hdmi_cec_f
>    * Bridge Connector Initialisation
>    */
>   
> -static void drm_bridge_connector_put_bridges(struct drm_device *dev, void *data)
> -{
> -	struct drm_bridge_connector *bridge_connector = (struct drm_bridge_connector *)data;
> -
> -	drm_bridge_put(bridge_connector->bridge_edid);
> -	drm_bridge_put(bridge_connector->bridge_hpd);
> -	drm_bridge_put(bridge_connector->bridge_detect);
> -	drm_bridge_put(bridge_connector->bridge_modes);
> -	drm_bridge_put(bridge_connector->bridge_hdmi);
> -	drm_bridge_put(bridge_connector->bridge_hdmi_audio);
> -	drm_bridge_put(bridge_connector->bridge_dp_audio);
> -	drm_bridge_put(bridge_connector->bridge_hdmi_cec);
> -}
> -
>   /**
>    * drm_bridge_connector_init - Initialise a connector for a chain of bridges
>    * @drm: the DRM device
> @@ -652,15 +638,7 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   	struct drm_bridge_connector *bridge_connector;
>   	struct drm_connector *connector;
>   	struct i2c_adapter *ddc = NULL;
> -	struct drm_bridge *panel_bridge      __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_edid       __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_hpd        __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_detect     __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_modes      __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_hdmi       __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_hdmi_audio __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_dp_audio   __free(drm_bridge_put) = NULL;
> -	struct drm_bridge *bridge_hdmi_cec   __free(drm_bridge_put) = NULL;
> +	struct drm_bridge *panel_bridge = NULL;
>   	unsigned int supported_formats = BIT(HDMI_COLORSPACE_RGB);
>   	unsigned int max_bpc = 8;
>   	bool support_hdcp = false;
> @@ -671,10 +649,6 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   	if (!bridge_connector)
>   		return ERR_PTR(-ENOMEM);
>   
> -	ret = drmm_add_action(drm, drm_bridge_connector_put_bridges, bridge_connector);
> -	if (ret)
> -		return ERR_PTR(ret);
> -
>   	bridge_connector->encoder = encoder;
>   
>   	/*
> @@ -698,30 +672,22 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   		if (!bridge->ycbcr_420_allowed)
>   			connector->ycbcr_420_allowed = false;
>   
> -		if (bridge->ops & DRM_BRIDGE_OP_EDID) {
> -			drm_bridge_put(bridge_edid);
> -			bridge_edid = drm_bridge_get(bridge);
> -		}
> -		if (bridge->ops & DRM_BRIDGE_OP_HPD) {
> -			drm_bridge_put(bridge_hpd);
> -			bridge_hpd = drm_bridge_get(bridge);
> -		}
> -		if (bridge->ops & DRM_BRIDGE_OP_DETECT) {
> -			drm_bridge_put(bridge_detect);
> -			bridge_detect = drm_bridge_get(bridge);
> -		}
> -		if (bridge->ops & DRM_BRIDGE_OP_MODES) {
> -			drm_bridge_put(bridge_modes);
> -			bridge_modes = drm_bridge_get(bridge);
> -		}
> +		if (bridge->ops & DRM_BRIDGE_OP_EDID)
> +			bridge_connector->bridge_edid = bridge;
> +		if (bridge->ops & DRM_BRIDGE_OP_HPD)
> +			bridge_connector->bridge_hpd = bridge;
> +		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
> +			bridge_connector->bridge_detect = bridge;
> +		if (bridge->ops & DRM_BRIDGE_OP_MODES)
> +			bridge_connector->bridge_modes = bridge;
>   		if (bridge->ops & DRM_BRIDGE_OP_HDMI) {
> -			if (bridge_hdmi)
> +			if (bridge_connector->bridge_hdmi)
>   				return ERR_PTR(-EBUSY);
>   			if (!bridge->funcs->hdmi_write_infoframe ||
>   			    !bridge->funcs->hdmi_clear_infoframe)
>   				return ERR_PTR(-EINVAL);
>   
> -			bridge_hdmi = drm_bridge_get(bridge);
> +			bridge_connector->bridge_hdmi = bridge;
>   
>   			if (bridge->supported_formats)
>   				supported_formats = bridge->supported_formats;
> @@ -730,10 +696,10 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   		}
>   
>   		if (bridge->ops & DRM_BRIDGE_OP_HDMI_AUDIO) {
> -			if (bridge_hdmi_audio)
> +			if (bridge_connector->bridge_hdmi_audio)
>   				return ERR_PTR(-EBUSY);
>   
> -			if (bridge_dp_audio)
> +			if (bridge_connector->bridge_dp_audio)
>   				return ERR_PTR(-EBUSY);
>   
>   			if (!bridge->hdmi_audio_max_i2s_playback_channels &&
> @@ -744,14 +710,14 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   			    !bridge->funcs->hdmi_audio_shutdown)
>   				return ERR_PTR(-EINVAL);
>   
> -			bridge_hdmi_audio = drm_bridge_get(bridge);
> +			bridge_connector->bridge_hdmi_audio = bridge;
>   		}
>   
>   		if (bridge->ops & DRM_BRIDGE_OP_DP_AUDIO) {
> -			if (bridge_dp_audio)
> +			if (bridge_connector->bridge_dp_audio)
>   				return ERR_PTR(-EBUSY);
>   
> -			if (bridge_hdmi_audio)
> +			if (bridge_connector->bridge_hdmi_audio)
>   				return ERR_PTR(-EBUSY);
>   
>   			if (!bridge->hdmi_audio_max_i2s_playback_channels &&
> @@ -762,7 +728,7 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   			    !bridge->funcs->dp_audio_shutdown)
>   				return ERR_PTR(-EINVAL);
>   
> -			bridge_dp_audio = drm_bridge_get(bridge);
> +			bridge_connector->bridge_dp_audio = bridge;
>   		}
>   
>   		if (bridge->ops & DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER) {
> @@ -773,10 +739,10 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   		}
>   
>   		if (bridge->ops & DRM_BRIDGE_OP_HDMI_CEC_ADAPTER) {
> -			if (bridge_hdmi_cec)
> +			if (bridge_connector->bridge_hdmi_cec)
>   				return ERR_PTR(-EBUSY);
>   
> -			bridge_hdmi_cec = drm_bridge_get(bridge);
> +			bridge_connector->bridge_hdmi_cec = bridge;
>   
>   			if (!bridge->funcs->hdmi_cec_enable ||
>   			    !bridge->funcs->hdmi_cec_log_addr ||
> @@ -796,7 +762,7 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   			ddc = bridge->ddc;
>   
>   		if (drm_bridge_is_panel(bridge))
> -			panel_bridge = drm_bridge_get(bridge);
> +			panel_bridge = bridge;
>   
>   		if (bridge->support_hdcp)
>   			support_hdcp = true;
> @@ -805,13 +771,13 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   	if (connector_type == DRM_MODE_CONNECTOR_Unknown)
>   		return ERR_PTR(-EINVAL);
>   
> -	if (bridge_hdmi) {
> +	if (bridge_connector->bridge_hdmi) {
>   		if (!connector->ycbcr_420_allowed)
>   			supported_formats &= ~BIT(HDMI_COLORSPACE_YUV420);
>   
>   		ret = drmm_connector_hdmi_init(drm, connector,
> -					       bridge_hdmi->vendor,
> -					       bridge_hdmi->product,
> +					       bridge_connector->bridge_hdmi->vendor,
> +					       bridge_connector->bridge_hdmi->product,
>   					       &drm_bridge_connector_funcs,
>   					       &drm_bridge_connector_hdmi_funcs,
>   					       connector_type, ddc,
> @@ -827,14 +793,15 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   			return ERR_PTR(ret);
>   	}
>   
> -	if (bridge_hdmi_audio || bridge_dp_audio) {
> +	if (bridge_connector->bridge_hdmi_audio ||
> +	    bridge_connector->bridge_dp_audio) {
>   		struct device *dev;
>   		struct drm_bridge *bridge;
>   
> -		if (bridge_hdmi_audio)
> -			bridge = bridge_hdmi_audio;
> +		if (bridge_connector->bridge_hdmi_audio)
> +			bridge = bridge_connector->bridge_hdmi_audio;
>   		else
> -			bridge = bridge_dp_audio;
> +			bridge = bridge_connector->bridge_dp_audio;
>   
>   		dev = bridge->hdmi_audio_dev;
>   
> @@ -848,9 +815,9 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   			return ERR_PTR(ret);
>   	}
>   
> -	if (bridge_hdmi_cec &&
> -	    bridge_hdmi_cec->ops & DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER) {
> -		struct drm_bridge *bridge = bridge_hdmi_cec;
> +	if (bridge_connector->bridge_hdmi_cec &&
> +	    bridge_connector->bridge_hdmi_cec->ops & DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER) {
> +		struct drm_bridge *bridge = bridge_connector->bridge_hdmi_cec;
>   
>   		ret = drmm_connector_hdmi_cec_notifier_register(connector,
>   								NULL,
> @@ -859,9 +826,9 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   			return ERR_PTR(ret);
>   	}
>   
> -	if (bridge_hdmi_cec &&
> -	    bridge_hdmi_cec->ops & DRM_BRIDGE_OP_HDMI_CEC_ADAPTER) {
> -		struct drm_bridge *bridge = bridge_hdmi_cec;
> +	if (bridge_connector->bridge_hdmi_cec &&
> +	    bridge_connector->bridge_hdmi_cec->ops & DRM_BRIDGE_OP_HDMI_CEC_ADAPTER) {
> +		struct drm_bridge *bridge = bridge_connector->bridge_hdmi_cec;
>   
>   		ret = drmm_connector_hdmi_cec_register(connector,
>   						       &drm_bridge_connector_hdmi_cec_funcs,
> @@ -874,9 +841,9 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   
>   	drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
>   
> -	if (bridge_hpd)
> +	if (bridge_connector->bridge_hpd)
>   		connector->polled = DRM_CONNECTOR_POLL_HPD;
> -	else if (bridge_detect)
> +	else if (bridge_connector->bridge_detect)
>   		connector->polled = DRM_CONNECTOR_POLL_CONNECT
>   				  | DRM_CONNECTOR_POLL_DISCONNECT;
>   
> @@ -887,15 +854,6 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
>   	    IS_ENABLED(CONFIG_DRM_DISPLAY_HDCP_HELPER))
>   		drm_connector_attach_content_protection_property(connector, true);
>   
> -	bridge_connector->bridge_edid       = drm_bridge_get(bridge_edid);
> -	bridge_connector->bridge_hpd        = drm_bridge_get(bridge_hpd);
> -	bridge_connector->bridge_detect     = drm_bridge_get(bridge_detect);
> -	bridge_connector->bridge_modes      = drm_bridge_get(bridge_modes);
> -	bridge_connector->bridge_hdmi       = drm_bridge_get(bridge_hdmi);
> -	bridge_connector->bridge_hdmi_audio = drm_bridge_get(bridge_hdmi_audio);
> -	bridge_connector->bridge_dp_audio   = drm_bridge_get(bridge_dp_audio);
> -	bridge_connector->bridge_hdmi_cec   = drm_bridge_get(bridge_hdmi_cec);
> -
>   	return connector;
>   }
>   EXPORT_SYMBOL_GPL(drm_bridge_connector_init);
> 

-- 
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com