Subject: Re: [PATCH RESEND v3 1/6] drm/connector: report IRQ_HPD events to drm_connector_oob_hotplug_event()

From: Maxime Ripard <[email-masked]>
Date: Fri, 29 May 2026 16:04:46 +0200

On Thu, May 21, 2026 at 03:05:11PM +0300, Dmitry Baryshkov wrote:
> On Thu, May 21, 2026 at 09:47:29AM +0200, Maxime Ripard wrote:
> > On Wed, May 13, 2026 at 09:23:21PM +0300, 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 ported through the bits in the AltMode VDOs.
> > > 
> > > Extend the drm_connector_oob_hotplug_event() interface and report IRQ
> > > events to the DisplayPort Sink drivers.
> > > 
> > > Signed-off-by: Dmitry Baryshkov <[email-masked]>
> > > ---
> > >  drivers/gpu/drm/drm_connector.c          |  5 ++++-
> > >  drivers/usb/typec/altmodes/displayport.c | 15 +++++++++++----
> > >  include/drm/drm_connector.h              | 19 ++++++++++++++++++-
> > >  3 files changed, 33 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > > index 47dc53c4a738..edee9daccd51 100644
> > > --- a/drivers/gpu/drm/drm_connector.c
> > > +++ b/drivers/gpu/drm/drm_connector.c
> > > @@ -3510,6 +3510,8 @@ 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
> > >   * @connector_fwnode: fwnode_handle to report the event on
> > >   * @status: hot plug detect logical state
> > > + * @extra_status: additional information provided 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
> > > @@ -3520,7 +3522,8 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
> > >   * 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)
> > > +				     enum drm_connector_status status,
> > > +				     enum drm_connector_status_extra extra_status)
> > >  {
> > >  	struct drm_connector *connector;
> > >  
> > > diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
> > > index 35d9c3086990..7182a8e2e710 100644
> > > --- a/drivers/usb/typec/altmodes/displayport.c
> > > +++ b/drivers/usb/typec/altmodes/displayport.c
> > > @@ -189,7 +189,9 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
> > >  	} else {
> > >  		drm_connector_oob_hotplug_event(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);
> > 
> > Since the extra status itself, and what the options mean, are DP specific, do we really want to
> > extend drm_connector_oob_hotplug_event()? I think I'd prefer to have a DP specific variant, with its
> > own set of parameters.
> 
> I can try arguing that drm_connector_oob_hotplug_event() is DP-specific,
> there are no other users for it, only the DP AltMode driver.
> 
> Anyway, do you just mean new API here or new API and a new connector
> callback?

If drm_connector_oob_hotplug_event is truly only used for DP, then I
don't mind keeping it as is but we should make it more obvious and
document it, both in the function documentation, but also by having a
better name for the extra status. drm_connector_dp_oob_status maybe?

Maxime