[PATCH] drm/xe/display: Block hpd during suspend

[Maarten Lankhorst]

Den 2025-07-18 kl. 07:21, skrev Dibin Moolakadan Subrahmanian:
> On 17-07-2025 17:24, Maarten Lankhorst wrote:
>> Hey,
>>
>> When I looked at enabling -RT for Xe yesterday, I noticed this trace.
>>
>> https://intel-gfx-ci.01.org/tree/intel-xe/xe-pw-151626v2/shard-bmg-6/igt@kms_cursor_crc@cursor-suspend@pipe-d-hdmi-a-3.html#dmesg-warnings488
>>
>> I independently discovered the bug as a result, and sent this patch to actually disable the irqs.
>>
>> https://patchwork.freedesktop.org/series/151728/
>>
>> If you have a reproducer, can  you confirm this fixes it?
> I was not able to reproduce this issue , but I did change to trigger hpd in suspend path
> to test my changes.
Can you try without your changes? It should be unnecessary with this change.

Kind regards,
~Maarten
>> Kind regards,
>> ~Maarten
>>
>> Den 2025-07-17 kl. 10:54, skrev Dibin Moolakadan Subrahmanian:
>>> 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  'intel_hpd_block_all_encoders()' and
>>> 'intel_hpd_unblock_all_encoders()' functions, which iterate over all
>>> encoders and block/unblock HPD respectively.
>>>
>>> These are used to:
>>> - Block HPD IRQs before calling 'intel_hpd_cancel_work' in suspend
>>> - Unblock HPD IRQs after 'intel_hpd_init' in resume
>>>
>>> This will prevent 'dig_port_work' being scheduled during display
>>> suspend.
>>>
>>> Continuation of previous patch discussion:
>>> https://patchwork.freedesktop.org/patch/663964/
>>>
>>> Signed-off-by: Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian at intel.com>
>>> ---
>>>  drivers/gpu/drm/i915/display/intel_hotplug.c | 24 ++++++++++++++++++--
>>>  drivers/gpu/drm/i915/display/intel_hotplug.h |  2 ++
>>>  drivers/gpu/drm/xe/display/xe_display.c      |  4 ++++
>>>  3 files changed, 28 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.c b/drivers/gpu/drm/i915/display/intel_hotplug.c
>>> index 265aa97fcc75..7ffd8ded1c26 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_hotplug.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_hotplug.c
>>> @@ -223,6 +223,28 @@ queue_detection_work(struct intel_display *display, struct work_struct *work)
>>>  	return queue_work(display->wq.unordered, work);
>>>  }
>>>  
>>> +void intel_hpd_unblock_all_encoders(struct intel_display *display)
>>> +{
>>> +	struct intel_encoder *encoder;
>>> +
>>> +	if (!HAS_DISPLAY(display))
>>> +		return;
>>> +
>>> +	for_each_intel_encoder(display->drm, encoder)
>>> +		intel_hpd_unblock(encoder);
>>> +}
>>> +
>>> +void intel_hpd_block_all_encoders(struct intel_display *display)
>>> +{
>>> +	struct intel_encoder *encoder;
>>> +
>>> +	if (!HAS_DISPLAY(display))
>>> +		return;
>>> +
>>> +	for_each_intel_encoder(display->drm, encoder)
>>> +		intel_hpd_block(encoder);
>>> +}
>>> +
>>>  static void
>>>  intel_hpd_irq_storm_switch_to_polling(struct intel_display *display)
>>>  {
>>> @@ -971,8 +993,6 @@ void intel_hpd_cancel_work(struct intel_display *display)
>>>  
>>>  	spin_lock_irq(&display->irq.lock);
>>>  
>>> -	drm_WARN_ON(display->drm, get_blocked_hpd_pin_mask(display));
>>> -
>>>  	display->hotplug.long_hpd_pin_mask = 0;
>>>  	display->hotplug.short_hpd_pin_mask = 0;
>>>  	display->hotplug.event_bits = 0;
>>> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.h b/drivers/gpu/drm/i915/display/intel_hotplug.h
>>> index edc41c9d3d65..3938c93d2385 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_block_all_encoders(struct intel_display *display);
>>> +void intel_hpd_unblock_all_encoders(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..51584ea3ed09 100644
>>> --- a/drivers/gpu/drm/xe/display/xe_display.c
>>> +++ b/drivers/gpu/drm/xe/display/xe_display.c
>>> @@ -340,6 +340,8 @@ void xe_display_pm_suspend(struct xe_device *xe)
>>>  
>>>  	xe_display_flush_cleanup_work(xe);
>>>  
>>> +	intel_hpd_block_all_encoders(display);
>>> +
>>>  	intel_hpd_cancel_work(display);
>>>  
>>>  	if (has_display(xe)) {
>>> @@ -471,6 +473,8 @@ void xe_display_pm_resume(struct xe_device *xe)
>>>  
>>>  	intel_hpd_init(display);
>>>  
>>> +	intel_hpd_unblock_all_encoders(display);
>>> +
>>>  	if (has_display(xe)) {
>>>  		intel_display_driver_resume(display);
>>>  		drm_kms_helper_poll_enable(&xe->drm);
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