[PATCH v2] drm/xe/display: Block hpd during suspend

[Maarten Lankhorst]

Hey,

Den 2025-07-23 kl. 15:19, skrev Rodrigo Vivi:
> On Wed, Jul 23, 2025 at 12:38:08PM +0300, Imre Deak wrote:
>> On Wed, Jul 23, 2025 at 02:59:46PM +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  'intel_encoder_block_all_hpds' and
>>> 'intel_encoder_unblock_all_hpds' 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
>>>   and shutdown
>>> - 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/
>>>
>>> Changes in v2:
>>>  - Add 'intel_encoder_block_all_hpds' to 'xe_display_pm_shutdown'
>>>  - Add 'intel_hpd_cancel_work' to 'xe_display_fini_early' to cancel
>>>    any HPD pending work at late driver removal
>>>
>>> Signed-off-by: Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian at intel.com>
>>> ---
>>>  drivers/gpu/drm/i915/display/intel_encoder.c | 23 ++++++++++++++++++++
>>>  drivers/gpu/drm/i915/display/intel_encoder.h |  3 +++
>>>  drivers/gpu/drm/i915/display/intel_hotplug.c |  2 --
>>>  drivers/gpu/drm/xe/display/xe_display.c      |  6 +++++
>>>  4 files changed, 32 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_encoder.c b/drivers/gpu/drm/i915/display/intel_encoder.c
>>> index 0b7bd26f4339..4e2b77b87678 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_encoder.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_encoder.c
>>> @@ -8,6 +8,7 @@
>>>  #include "intel_display_core.h"
>>>  #include "intel_display_types.h"
>>>  #include "intel_encoder.h"
>>> +#include "intel_hotplug.h"
>>>  
>>>  static void intel_encoder_link_check_work_fn(struct work_struct *work)
>>>  {
>>> @@ -37,6 +38,28 @@ void intel_encoder_link_check_queue_work(struct intel_encoder *encoder, int dela
>>>  			 &encoder->link_check_work, msecs_to_jiffies(delay_ms));
>>>  }
>>>  
>>> +void intel_encoder_unblock_all_hpds(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_encoder_block_all_hpds(struct intel_display *display)
>>> +{
>>> +	struct intel_encoder *encoder;
>>> +
>>> +	if (!HAS_DISPLAY(display))
>>> +		return;
>>> +
>>> +	for_each_intel_encoder(display->drm, encoder)
>>> +		intel_hpd_block(encoder);
>>> +}
>>> +
>>>  void intel_encoder_suspend_all(struct intel_display *display)
>>>  {
>>>  	struct intel_encoder *encoder;
>>> diff --git a/drivers/gpu/drm/i915/display/intel_encoder.h b/drivers/gpu/drm/i915/display/intel_encoder.h
>>> index 3fa5589f0b1c..e1d3aeab7c00 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_encoder.h
>>> +++ b/drivers/gpu/drm/i915/display/intel_encoder.h
>>> @@ -17,4 +17,7 @@ void intel_encoder_link_check_flush_work(struct intel_encoder *encoder);
>>>  void intel_encoder_suspend_all(struct intel_display *display);
>>>  void intel_encoder_shutdown_all(struct intel_display *display);
>>>  
>>> +void intel_encoder_block_all_hpds(struct intel_display *display);
>>> +void intel_encoder_unblock_all_hpds(struct intel_display *display);
>>> +
>>>  #endif /* __INTEL_ENCODER_H__ */
>>> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.c b/drivers/gpu/drm/i915/display/intel_hotplug.c
>>> index 265aa97fcc75..c69b535497bf 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_hotplug.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_hotplug.c
>>> @@ -971,8 +971,6 @@ 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/xe/display/xe_display.c b/drivers/gpu/drm/xe/display/xe_display.c
>>> index e2e0771cf274..9e984a045059 100644
>>> --- a/drivers/gpu/drm/xe/display/xe_display.c
>>> +++ b/drivers/gpu/drm/xe/display/xe_display.c
>>> @@ -96,6 +96,7 @@ static void xe_display_fini_early(void *arg)
>>>  	if (!xe->info.probe_display)
>>>  		return;
>>>  
>>> +	intel_hpd_cancel_work(display);
>>>  	intel_display_driver_remove_nogem(display);
>>>  	intel_display_driver_remove_noirq(display);
>>>  	intel_opregion_cleanup(display);
>>> @@ -340,6 +341,8 @@ void xe_display_pm_suspend(struct xe_device *xe)
>>>  
>>>  	xe_display_flush_cleanup_work(xe);
>>>  
>>> +	intel_encoder_block_all_hpds(display);
>>> +
>>>  	intel_hpd_cancel_work(display);
>>>  
>>>  	if (has_display(xe)) {
>>> @@ -369,6 +372,7 @@ void xe_display_pm_shutdown(struct xe_device *xe)
>>>  	}
>>>  
>>>  	xe_display_flush_cleanup_work(xe);
>>> +	intel_encoder_block_all_hpds(display);
>>
>> MST still needs HPD IRQs for side-band messaging, so the HPD IRQs must
>> be blocked only after intel_dp_mst_suspend().
>>
>> Otherwise the patch looks ok to me, so with the above fixed and provided
>> that Maarten is ok to disable all display IRQs only later:
> 
> Also probably good to identify the patch as both xe and i915 in the subject
> drm/{i915,xe}/display:
> 
> and Maarten or Imre, any preference on which branch to go? any chance of
> conflicting with any of work you might be doing in any side?
> 
> From my side I believe that any conflict might be easy to handle, so
> 
> Acked-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> 
> from either side...
> 
>>
>> Reviewed-by: Imre Deak <imre.deak at intel.com>
We had a discussion on this approach, and it seems that completely disabling interrupts here like in i915 would fail too.

Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>

I don't mind either branch. As long as it applies. :-)