drm/xe/display: handle HPD polling in display runtime suspend/resume

In XE, display runtime suspend / resume routines are called only
if d3cold is allowed. This makes the driver unable to detect any
HPDs once the device goes into runtime suspend state in platforms
like LNL. Update the display runtime suspend / resume routines
to include HPD polling regardless of d3cold status.

While xe_display_pm_suspend/resume() performs steps during runtime
suspend/resume that shouldn't happen, like suspending MST and they
are missing other steps like enabling DC9, this patchset is meant
to keep the current behavior wrt. these, leaving the corresponding
updates for a follow-up

v2: have a separate function for display runtime s/r (Rodrigo)

v3: better streamlining of system s/r and runtime s/r calls (Imre)

v4: rebased
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240823112148.327015-4-vinod.govindapillai@intel.com

drivers/gpu/drm/xe/display/xe_display.c

@@ -308,6 +308,18 @@ static void xe_display_flush_cleanup_work(struct xe_device *xe)
 	}
 }
 
+/* TODO: System and runtime suspend/resume sequences will be sanitized as a follow-up. */
+void xe_display_pm_runtime_suspend(struct xe_device *xe)
+{
+	if (!xe->info.probe_display)
+		return;
+
+	if (xe->d3cold.allowed)
+		xe_display_pm_suspend(xe, true);
+
+	intel_hpd_poll_enable(xe);
+}
+
 void xe_display_pm_suspend(struct xe_device *xe, bool runtime)
 {
 	struct intel_display *display = &xe->display;
@@ -354,6 +366,17 @@ void xe_display_pm_suspend_late(struct xe_device *xe)
 	intel_display_power_suspend_late(xe);
 }
 
+void xe_display_pm_runtime_resume(struct xe_device *xe)
+{
+	if (!xe->info.probe_display)
+		return;
+
+	intel_hpd_poll_disable(xe);
+
+	if (xe->d3cold.allowed)
+		xe_display_pm_resume(xe, true);
+}
+
 void xe_display_pm_resume_early(struct xe_device *xe)
 {
 	if (!xe->info.probe_display)

drivers/gpu/drm/xe/display/xe_display.h

@@ -38,6 +38,8 @@ void xe_display_pm_suspend(struct xe_device *xe, bool runtime);
 void xe_display_pm_suspend_late(struct xe_device *xe);
 void xe_display_pm_resume_early(struct xe_device *xe);
 void xe_display_pm_resume(struct xe_device *xe, bool runtime);
+void xe_display_pm_runtime_suspend(struct xe_device *xe);
+void xe_display_pm_runtime_resume(struct xe_device *xe);
 
 #else
 
@@ -67,6 +69,8 @@ static inline void xe_display_pm_suspend(struct xe_device *xe, bool runtime) {}
 static inline void xe_display_pm_suspend_late(struct xe_device *xe) {}
 static inline void xe_display_pm_resume_early(struct xe_device *xe) {}
 static inline void xe_display_pm_resume(struct xe_device *xe, bool runtime) {}
+static inline void xe_display_pm_runtime_suspend(struct xe_device *xe) {}
+static inline void xe_display_pm_runtime_resume(struct xe_device *xe) {}
 
 #endif /* CONFIG_DRM_XE_DISPLAY */
 #endif /* _XE_DISPLAY_H_ */

drivers/gpu/drm/xe/xe_pm.c

@@ -366,9 +366,9 @@ int xe_pm_runtime_suspend(struct xe_device *xe)
 		xe_bo_runtime_pm_release_mmap_offset(bo);
 	mutex_unlock(&xe->mem_access.vram_userfault.lock);
 
-	if (xe->d3cold.allowed) {
-		xe_display_pm_suspend(xe, true);
+	xe_display_pm_runtime_suspend(xe);
 
+	if (xe->d3cold.allowed) {
 		err = xe_bo_evict_all(xe);
 		if (err)
 			goto out;
@@ -431,12 +431,14 @@ int xe_pm_runtime_resume(struct xe_device *xe)
 	for_each_gt(gt, xe, id)
 		xe_gt_resume(gt);
 
+	xe_display_pm_runtime_resume(xe);
+
 	if (xe->d3cold.allowed) {
-		xe_display_pm_resume(xe, true);
 		err = xe_bo_restore_user(xe);
 		if (err)
 			goto out;
 	}
+
 out:
 	lock_map_release(&xe_pm_runtime_lockdep_map);
 	xe_pm_write_callback_task(xe, NULL);