Defer vblank event handling while waiting for a pending flip

This is to avoid submitting more flips while we are waiting for pending
ones to complete.

Acked-by: Alex Deucher <alexander.deucher@amd.com>

4 files changed, 56 insertions, 8 deletions

diff --git a/src/amdgpu_drm_queue.c b/src/amdgpu_drm_queue.c
index f866082..b13d280 100644
--- a/src/amdgpu_drm_queue.c
+++ b/src/amdgpu_drm_queue.c
@@ -118,6 +118,30 @@ amdgpu_drm_vblank_handler(int fd, unsigned int frame, unsigned int sec,
 }
 
 /*
+ * Handle deferred DRM vblank events
+ *
+ * This function must be called after amdgpu_drm_wait_pending_flip, once
+ * it's safe to attempt queueing a flip again
+ */
+void
+amdgpu_drm_queue_handle_deferred(xf86CrtcPtr crtc)
+{
+	drmmode_crtc_private_ptr drmmode_crtc = crtc->driver_private;
+	struct amdgpu_drm_queue_entry *e, *tmp;
+
+	if (drmmode_crtc->wait_flip_nesting_level == 0 ||
+	    --drmmode_crtc->wait_flip_nesting_level > 0)
+		return;
+
+	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_signalled, list) {
+		drmmode_crtc_private_ptr drmmode_crtc = e->crtc->driver_private;
+
+		if (drmmode_crtc->wait_flip_nesting_level == 0)
+			amdgpu_drm_queue_handle_one(e);
+	}
+}
+
+/*
  * Enqueue a potential drm response; when the associated response
  * appears, we've got data to pass to the handler from here
  */
@@ -191,6 +215,13 @@ amdgpu_drm_abort_entry(uintptr_t seq)
 	if (seq == AMDGPU_DRM_QUEUE_ERROR)
 		return;
 
+	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_signalled, list) {
+		if (e->seq == seq) {
+			amdgpu_drm_abort_one(e);
+			return;
+		}
+	}
+
 	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_queue, list) {
 		if (e->seq == seq) {
 			amdgpu_drm_abort_one(e);
@@ -229,8 +260,12 @@ amdgpu_drm_handle_event(int fd, drmEventContext *event_context)
 	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_flip_signalled, list)
 		amdgpu_drm_queue_handle_one(e);
 
-	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_signalled, list)
-		amdgpu_drm_queue_handle_one(e);
+	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_signalled, list) {
+		drmmode_crtc_private_ptr drmmode_crtc = e->crtc->driver_private;
+
+		if (drmmode_crtc->wait_flip_nesting_level == 0)
+			amdgpu_drm_queue_handle_one(e);
+	}
 
 	return r;
 }
@@ -244,6 +279,8 @@ void amdgpu_drm_wait_pending_flip(xf86CrtcPtr crtc)
 	AMDGPUEntPtr pAMDGPUEnt = AMDGPUEntPriv(crtc->scrn);
 	struct amdgpu_drm_queue_entry *e, *tmp;
 
+	drmmode_crtc->wait_flip_nesting_level++;
+
 	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_flip_signalled, list)
 		amdgpu_drm_queue_handle_one(e);
 
diff --git a/src/amdgpu_drm_queue.h b/src/amdgpu_drm_queue.h
index 48ba9ab..4e7c8f4 100644
--- a/src/amdgpu_drm_queue.h
+++ b/src/amdgpu_drm_queue.h
@@ -42,6 +42,7 @@ typedef void (*amdgpu_drm_handler_proc)(xf86CrtcPtr crtc, uint32_t seq,
 					uint64_t usec, void *data);
 typedef void (*amdgpu_drm_abort_proc)(xf86CrtcPtr crtc, void *data);
 
+void amdgpu_drm_queue_handle_deferred(xf86CrtcPtr crtc);
 uintptr_t amdgpu_drm_queue_alloc(xf86CrtcPtr crtc, ClientPtr client,
 				 uint64_t id, void *data,
 				 amdgpu_drm_handler_proc handler,
diff --git a/src/drmmode_display.c b/src/drmmode_display.c
index 167b300..9919c09 100644
--- a/src/drmmode_display.c
+++ b/src/drmmode_display.c
@@ -305,6 +305,9 @@ drmmode_do_crtc_dpms(xf86CrtcPtr crtc, int mode)
 				nominal_frame_rate /= pix_in_frame;
 			drmmode_crtc->dpms_last_fps = nominal_frame_rate;
 		}
+
+		drmmode_crtc->dpms_mode = mode;
+		amdgpu_drm_queue_handle_deferred(crtc);
 	} else if (drmmode_crtc->dpms_mode != DPMSModeOn && mode == DPMSModeOn) {
 		/*
 		 * Off->On transition: calculate and accumulate the
@@ -322,8 +325,9 @@ drmmode_do_crtc_dpms(xf86CrtcPtr crtc, int mode)
 			drmmode_crtc->interpolated_vblanks += delta_seq;
 
 		}
+
+		drmmode_crtc->dpms_mode = DPMSModeOn;
 	}
-	drmmode_crtc->dpms_mode = mode;
 }
 
 static void
@@ -1415,6 +1419,7 @@ done:
 		}
 	}
 
+	amdgpu_drm_queue_handle_deferred(crtc);
 	return ret;
 }
 
@@ -2320,11 +2325,6 @@ drmmode_output_set_tear_free(AMDGPUEntPtr pAMDGPUEnt,
 	drmmode_output->tear_free = tear_free;
 
 	if (crtc) {
-		/* Wait for pending flips before drmmode_set_mode_major calls
-		 * drmmode_crtc_update_tear_free, to prevent a nested
-		 * drmHandleEvent call, which would hang
-		 */
-		amdgpu_drm_wait_pending_flip(crtc);
 		drmmode_set_mode_major(crtc, &crtc->mode, crtc->rotation,
 				       crtc->x, crtc->y);
 	}
@@ -3864,6 +3864,7 @@ Bool amdgpu_do_pageflip(ScrnInfoPtr scrn, ClientPtr client,
 	drmmode_crtc_private_ptr drmmode_crtc = config->crtc[0]->driver_private;
 	uint32_t flip_flags = flip_sync == FLIP_ASYNC ? DRM_MODE_PAGE_FLIP_ASYNC : 0;
 	drmmode_flipdata_ptr flipdata;
+	Bool handle_deferred = FALSE;
 	uintptr_t drm_queue_seq = 0;
 	struct drmmode_fb *fb;
 	int i = 0;
@@ -3946,6 +3947,7 @@ Bool amdgpu_do_pageflip(ScrnInfoPtr scrn, ClientPtr client,
 
 			if (drmmode_crtc->scanout_update_pending) {
 				amdgpu_drm_wait_pending_flip(crtc);
+				handle_deferred = TRUE;
 				amdgpu_drm_abort_entry(drmmode_crtc->scanout_update_pending);
 				drmmode_crtc->scanout_update_pending = 0;
 			}
@@ -3981,6 +3983,8 @@ Bool amdgpu_do_pageflip(ScrnInfoPtr scrn, ClientPtr client,
 		drm_queue_seq = 0;
 	}
 
+	if (handle_deferred)
+		amdgpu_drm_queue_handle_deferred(ref_crtc);
 	if (flipdata->flip_count > 0)
 		return TRUE;
 
@@ -4000,5 +4004,7 @@ error:
 
 	xf86DrvMsg(scrn->scrnIndex, X_WARNING, "Page flip failed: %s\n",
 		   strerror(errno));
+	if (handle_deferred)
+		amdgpu_drm_queue_handle_deferred(ref_crtc);
 	return FALSE;
 }
diff --git a/src/drmmode_display.h b/src/drmmode_display.h
index 5618c6b..27610d5 100644
--- a/src/drmmode_display.h
+++ b/src/drmmode_display.h
@@ -119,6 +119,10 @@ typedef struct {
 
 	/* Modeset needed for DPMS on */
 	Bool need_modeset;
+	/* For keeping track of nested calls to drm_wait_pending_flip /
+	 * drm_queue_handle_deferred
+	 */
+	int wait_flip_nesting_level;
 	/* A flip to this FB is pending for this CRTC */
 	struct drmmode_fb *flip_pending;
 	/* The FB currently being scanned out by this CRTC, if any */