Re: [PATCH v5 1/8] drm/connector: report out-of-band IRQ_HPD events

[Chaoyi Chen]

Hi Dmitry,

On 9/20/2026 11:01 PM, Dmitry Baryshkov wrote:
> The DisplayPort standard defines a special kind of events called IRQ.
> These events are used to notify DP Source about the events on the Sink
> side. It is extremely important for DP MST handling, where the MST
> events are reported through this IRQ.
> 
> In case of the USB-C DP AltMode there is no actual HPD pulse, but the
> events are reported through the bits in the AltMode VDOs.
> 
> Rename drm_connector_oob_hotplug_event() to drm_connector_dp_oob_status()
> and extend its interface to report IRQ events to the DisplayPort Sink
> drivers.
> 
> Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/drm_connector.c          | 20 ++++++++++++--------
>  drivers/usb/typec/altmodes/displayport.c | 23 +++++++++++++++--------
>  include/drm/drm_connector.h              | 21 +++++++++++++++++++--
>  3 files changed, 46 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 8b4baed060f3..5d4945ea1e95 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -3672,20 +3672,24 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
>  }
>  
>  /**
> - * drm_connector_oob_hotplug_event - Report out-of-band hotplug event to connector
> + * drm_connector_dp_oob_status - Report out-of-band hotplug event to DisplayPort connector
>   * @connector_fwnode: fwnode_handle to report the event on
>   * @status: hot plug detect logical state
> + * @event: additional event reported by the sink without changing the HPD state
> + * (or in addition to such a change).
>   *
> - * On some hardware a hotplug event notification may come from outside the display
> - * driver / device. An example of this is some USB Type-C setups where the hardware
> - * muxes the DisplayPort data and aux-lines but does not pass the altmode HPD
> - * status bit to the GPU's DP HPD pin.
> + * In some cases when DisplayPort signals are being routed through the USB
> + * Type-C port the hotplug event notifications come from outside of the display
> + * driver / device. In this case hardware muxes the DisplayPort data and
> + * AUX-lines but does not pass the altmode HPD status bit to the GPU's DP HPD
> + * pin.
>   *
>   * This function can be used to report these out-of-band events after obtaining
>   * a drm_connector reference through calling drm_connector_find_by_fwnode().
>   */
> -void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
> -				     enum drm_connector_status status)
> +void drm_connector_dp_oob_status(struct fwnode_handle *connector_fwnode,
> +				 enum drm_connector_status status,
> +				 enum drm_connector_dp_event event)
>  {
>  	struct drm_connector *connector;
>  
> @@ -3698,7 +3702,7 @@ void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
>  
>  	drm_connector_put(connector);
>  }
> -EXPORT_SYMBOL(drm_connector_oob_hotplug_event);
> +EXPORT_SYMBOL(drm_connector_dp_oob_status);
>  
>  /**
>   * drm_connector_get_color_format - Return connector color format of @conn_state
> diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
> index 51c92dd887ab..344a13c2a296 100644
> --- a/drivers/usb/typec/altmodes/displayport.c
> +++ b/drivers/usb/typec/altmodes/displayport.c
> @@ -187,9 +187,11 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
>  				dp->pending_irq_hpd = true;
>  		}
>  	} else {
> -		drm_connector_oob_hotplug_event(dp->connector_fwnode,
> +		drm_connector_dp_oob_status(dp->connector_fwnode,
>  						hpd ? connector_status_connected :
> -						      connector_status_disconnected);
> +						      connector_status_disconnected,
> +						(hpd && irq_hpd) ? DRM_CONNECTOR_DP_IRQ_HPD :
> +								   DRM_CONNECTOR_NO_EXTRA_STATUS);

The CI is complaining about the alignment issue here. 
I think this needs to be fixed?

>  		dp->hpd = hpd;
>  		sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
>  		if (hpd && irq_hpd) {
> @@ -211,8 +213,11 @@ static int dp_altmode_configured(struct dp_altmode *dp)
>  	 * configuration is complete to signal HPD.
>  	 */
>  	if (dp->pending_hpd) {
> -		drm_connector_oob_hotplug_event(dp->connector_fwnode,
> -						connector_status_connected);
> +		drm_connector_dp_oob_status(dp->connector_fwnode,
> +						connector_status_connected,
> +						dp->pending_irq_hpd ?
> +						DRM_CONNECTOR_DP_IRQ_HPD :
> +						DRM_CONNECTOR_NO_EXTRA_STATUS);
>  		sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
>  		dp->pending_hpd = false;
>  		if (dp->pending_irq_hpd) {
> @@ -396,8 +401,9 @@ static int dp_altmode_vdm(struct typec_altmode *alt,
>  			dp->data.status = 0;
>  			dp->data.conf = 0;
>  			if (dp->hpd) {
> -				drm_connector_oob_hotplug_event(dp->connector_fwnode,
> -								connector_status_disconnected);
> +				drm_connector_dp_oob_status(dp->connector_fwnode,
> +								connector_status_disconnected,
> +								DRM_CONNECTOR_NO_EXTRA_STATUS);
>  				dp->hpd = false;
>  				sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
>  			}
> @@ -844,8 +850,9 @@ void dp_altmode_remove(struct typec_altmode *alt)
>  	typec_altmode_put_plug(dp->plug_prime);
>  
>  	if (dp->connector_fwnode) {
> -		drm_connector_oob_hotplug_event(dp->connector_fwnode,
> -						connector_status_disconnected);
> +		drm_connector_dp_oob_status(dp->connector_fwnode,
> +						connector_status_disconnected,
> +						DRM_CONNECTOR_NO_EXTRA_STATUS);
>  
>  		fwnode_handle_put(dp->connector_fwnode);
>  	}
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index c61345e6fb08..906aaefca7e1 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -91,6 +91,22 @@ enum drm_connector_status {
>  	connector_status_unknown = 3,
>  };
>  
> +/**
> + * enum drm_connector_dp_event - additional events sent by the sink /
> + * display together or in replacement of the HPD status changes.
> + */
> +enum drm_connector_dp_event {
> +	/**
> +	 * @DRM_CONNECTOR_NO_EXTRA_STATUS: No additional status reported.
> +	 */
> +	DRM_CONNECTOR_NO_EXTRA_STATUS,
> +	/**
> +	 * @DRM_CONNECTOR_DP_IRQ_HPD: DisplayPort Sink has sent the
> +	 * IRQ_HPD (either by the HPD short pulse or via the AltMode event).
> +	 */
> +	DRM_CONNECTOR_DP_IRQ_HPD,
> +};
> +
>  /**
>   * enum drm_connector_registration_state - userspace registration status for
>   * a &drm_connector
> @@ -2703,8 +2719,9 @@ drm_connector_is_unregistered(struct drm_connector *connector)
>  		DRM_CONNECTOR_UNREGISTERED;
>  }
>  
> -void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
> -				     enum drm_connector_status status);
> +void drm_connector_dp_oob_status(struct fwnode_handle *connector_fwnode,
> +				 enum drm_connector_status status,
> +				 enum drm_connector_dp_event event);
>  enum drm_connector_color_format
>  drm_connector_get_color_format(const struct drm_connector_state *conn_state);
>  const char *drm_get_connector_type_name(unsigned int connector_type);
> 

-- 
Best, 
Chaoyi