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

[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);
-- 
2.43.0