[PATCH v2] drm/xe/display: Block hpd during suspend
Jani Nikula
jani.nikula at linux.intel.com
Tue Jul 29 09:44:47 UTC 2025
On Thu, 24 Jul 2025, Maarten Lankhorst <maarten.lankhorst at linux.intel.com> wrote:
> 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. :-)
Please do not merge through *any* tree.
How come you all think it's okay to add this xe specific thing, and make
unification harder?
intel_encoder_block_all_hpds() is *way* too specific for a high level
function. Neither xe nor i915 should never call something like that
directly.
BR,
Jani.
--
Jani Nikula, Intel
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