drm/{i915,xe}/display: Block hpd during suspend

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'.(Imre
   Deak)
 - Add 'intel_hpd_cancel_work' to 'xe_display_fini_early' to cancel
   any HPD pending work at late driver removal. (Imre Deak)

Changes in v3:
 - Move 'intel_encoder_block_all_hpds' after intel_dp_mst_suspend
   in 'xe_display_pm_shutdown'.(Imre Deak)

Signed-off-by: Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250724083928.2298199-1-dibin.moolakadan.subrahmanian@intel.com

1 files changed, 23 insertions, 0 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;