[PATCH] drm/xe/display: Avoid dig_port work during suspend

[Imre Deak]

On Tue, Jul 15, 2025 at 11:22:19AM +0530, Dibin Moolakadan Subrahmanian wrote:
>  It has been observed that during `xe_display_pm_suspend()` execution,
>  an HPD interrupt can still be triggered, resulting in `dig_port_work`
>  being scheduled. The issue arises when this work executes after
>  `xe_display_pm_suspend_late()`, by which time the display is fully
>  suspended.
> 
>  This can lead to errors such as "DC state mismatch", as the dig_port
>  work accesses display resources that are no longer available or
>  powered.
> 
>  To address this, introduce a new `ignore_dig_port` flag in the
>  hotplug in structure. This flag is checked in the interrupt handler to
>  prevent queuing of `dig_port_work` while the system is mid-suspend.
>  This behavior is consistent with the existing approach of suppressing
>  hotplug_work during suspend.
> 
> Signed-off-by: Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian at intel.com>
> ---
>  .../gpu/drm/i915/display/intel_display_core.h |  3 +++
>  drivers/gpu/drm/i915/display/intel_hotplug.c  | 22 ++++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_hotplug.h  |  2 ++
>  drivers/gpu/drm/xe/display/xe_display.c       |  4 ++++
>  4 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
> index 8c226406c5cd..376682c53798 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_core.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_core.h
> @@ -209,6 +209,9 @@ struct intel_hotplug {
>  	 * cue to ignore the long HPDs and can be set / unset using debugfs.
>  	 */
>  	bool ignore_long_hpd;
> +
> +	/* Flag to ignore dig_port work , used in suspend*/
> +	bool ignore_dig_port;
>  };
>  
>  struct intel_vbt_data {
> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.c b/drivers/gpu/drm/i915/display/intel_hotplug.c
> index 265aa97fcc75..b2891b7c3205 100644
> --- a/drivers/gpu/drm/i915/display/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/display/intel_hotplug.c
> @@ -223,6 +223,26 @@ queue_detection_work(struct intel_display *display, struct work_struct *work)
>  	return queue_work(display->wq.unordered, work);
>  }
>  
> +void intel_hpd_ignore_dig_port_work(struct intel_display *display, bool value)
> +{
> +	if (!HAS_DISPLAY(display))
> +		return;
> +
> +	spin_lock_irq(&display->irq.lock);
> +	display->hotplug.ignore_dig_port = value;
> +	spin_unlock_irq(&display->irq.lock);
> +}
> +
> +bool intel_hpd_can_queue_dig_port(struct intel_display *display)
> +{
> +	if (!HAS_DISPLAY(display))
> +		return FALSE;
> +
> +	lockdep_assert_held(&display->irq.lock);
> +
> +	return !display->hotplug.ignore_dig_port;
> +}
> +
>  static void
>  intel_hpd_irq_storm_switch_to_polling(struct intel_display *display)
>  {
> @@ -691,7 +711,7 @@ void intel_hpd_irq_handler(struct intel_display *display,
>  	 * queue for otherwise the flush_work in the pageflip code will
>  	 * deadlock.
>  	 */
> -	if (queue_dig)
> +	if (queue_dig && intel_hpd_can_queue_dig_port(display))
>  		queue_work(display->hotplug.dp_wq, &display->hotplug.dig_port_work);
>  	if (queue_hp)
>  		queue_delayed_detection_work(display,
> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.h b/drivers/gpu/drm/i915/display/intel_hotplug.h
> index edc41c9d3d65..9dc40ec7074c 100644
> --- a/drivers/gpu/drm/i915/display/intel_hotplug.h
> +++ b/drivers/gpu/drm/i915/display/intel_hotplug.h
> @@ -34,5 +34,7 @@ void intel_hpd_debugfs_register(struct intel_display *display);
>  void intel_hpd_enable_detection_work(struct intel_display *display);
>  void intel_hpd_disable_detection_work(struct intel_display *display);
>  bool intel_hpd_schedule_detection(struct intel_display *display);
> +void intel_hpd_ignore_dig_port_work(struct intel_display *display, bool value);
> +bool intel_hpd_can_queue_dig_port(struct intel_display *display);
>  
>  #endif /* __INTEL_HOTPLUG_H__ */
> diff --git a/drivers/gpu/drm/xe/display/xe_display.c b/drivers/gpu/drm/xe/display/xe_display.c
> index e2e0771cf274..2db71bd07c9f 100644
> --- a/drivers/gpu/drm/xe/display/xe_display.c
> +++ b/drivers/gpu/drm/xe/display/xe_display.c
> @@ -342,6 +342,8 @@ void xe_display_pm_suspend(struct xe_device *xe)
>  
>  	intel_hpd_cancel_work(display);
>  
> +	intel_hpd_ignore_dig_port_work(display, 1);
> +

The actual problem is that HPD IRQs are disabled too late in xe, this
should happen already before intel_hpd_cancel_work() is called.

>  	if (has_display(xe)) {
>  		intel_display_driver_suspend_access(display);
>  		intel_encoder_suspend_all(display);
> @@ -469,6 +471,8 @@ void xe_display_pm_resume(struct xe_device *xe)
>  	if (has_display(xe))
>  		intel_display_driver_resume_access(display);
>  
> +	intel_hpd_ignore_dig_port_work(display, 0);
> +
>  	intel_hpd_init(display);
>  
>  	if (has_display(xe)) {
> -- 
> 2.43.0
>