[PATCH] drm/xe/display: Avoid dig_port work during suspend
Dibin Moolakadan Subrahmanian
dibin.moolakadan.subrahmanian at intel.com
Wed Jul 16 12:45:32 UTC 2025
On 15-07-2025 20:55, Imre Deak wrote:
> 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.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.
>> 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.
Thanks for the suggestion , I will modify the patch accordingly.
>> 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
>>>>
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