On Tue, Jul 15, 2025 at 06:38:15PM +0530, Dibin Moolakadan Subrahmanian wrote:
>
> On 15-07-2025 15:10, Imre Deak wrote:
> > 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.
>
> You're right — the HPD IRQs appear to be disabled only later via
> xe_irq_suspend(xe),
> which is not early enough to prevent unwanted behavior during suspend.
>
> But unlike the HPD IRQ enable path, which uses function pointers from
> struct intel_hotplug_funcs, there doesn't appear to be a hook to disable IRQs
> early.
>
> The proposed approach mirrors how we're already handling hotplug_work,
> which is gated by the detection_work_enabled flag. This flag is cleared
> during suspend
> by intel_display_driver_disable_user_access().
The work should not run after intel_hpd_cancel_work() returns. To ensure
that it's the IRQs scheduling the work which should be disabled, before
intel_hpd_cancel_work() is called. For now, calling intel_hpd_block() on
all the encoders would be enough for that. intel_hpd_cancel_work() will
see then blocked IRQs, so the WARN about that should be removed from it.
> Regards,
> Dibin
>
> > > 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
> > >
