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

[Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian@intel.com>]

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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.

>
> 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@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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