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.subrahman...@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
>
