From 8f940358e40571bb0ba1a0e49c334705e17b3a21 Mon Sep 17 00:00:00 2001
From: Ricardo Steijn <61013287+RicArch97@users.noreply.github.com>
Date: Sun, 3 Nov 2024 22:05:46 +0100
Subject: [PATCH] tearing: avoid permanent disable due to rejected commits
 (#2295)

Currently, the cursor plane does not allow async page flips which causes tearing page flips to be rejected if the cursor was moved.

However, in games where no cursor image is present, the async page flips can still work as expected.

Instead of permanently disabling tearing after too many failures, test the output state first before each frame to see if we can commit with tearing_page_flip set to true.
---
 include/labwc.h            |  2 --
 src/common/scene-helpers.c | 28 +++++++++++++++++++++-------
 src/output.c               | 30 +-----------------------------
 3 files changed, 22 insertions(+), 38 deletions(-)

diff --git a/include/labwc.h b/include/labwc.h
index 09fdca7b..29f72c39 100644
--- a/include/labwc.h
+++ b/include/labwc.h
@@ -406,8 +406,6 @@ struct output {
 
 	bool leased;
 	bool gamma_lut_changed;
-
-	uint32_t nr_tearing_failures;
 };
 
 #undef LAB_NR_LAYERS
diff --git a/src/common/scene-helpers.c b/src/common/scene-helpers.c
index 6f3ee373..1eb670ed 100644
--- a/src/common/scene-helpers.c
+++ b/src/common/scene-helpers.c
@@ -107,19 +107,33 @@ lab_wlr_scene_output_commit(struct wlr_scene_output *scene_output,
 		return false;
 	}
 
+	if (state->tearing_page_flip) {
+		if (!wlr_output_test_state(wlr_output, state)) {
+			state->tearing_page_flip = false;
+		}
+	}
+
 	struct wlr_box additional_damage = {0};
 	if (state->buffer && is_magnify_on()) {
 		magnify(output, state->buffer, &additional_damage);
 	}
 
-	if (state == &output->pending) {
-		if (!output_state_commit(output)) {
-			wlr_log(WLR_INFO, "Failed to commit output %s",
-				wlr_output->name);
-			return false;
+	bool committed = wlr_output_commit_state(wlr_output, state);
+	/*
+	 * Handle case where the ouput state test for tearing succeeded,
+	 * but actual commit failed. Retry wihout tearing.
+	 */
+	if (!committed && state->tearing_page_flip) {
+		state->tearing_page_flip = false;
+		committed = wlr_output_commit_state(wlr_output, state);
+	}
+	if (committed) {
+		if (state == &output->pending) {
+			wlr_output_state_finish(&output->pending);
+			wlr_output_state_init(&output->pending);
 		}
-	} else if (!wlr_output_commit_state(wlr_output, state)) {
-		wlr_log(WLR_INFO, "Failed to commit state for output %s",
+	} else {
+		wlr_log(WLR_INFO, "Failed to commit output %s",
 			wlr_output->name);
 		return false;
 	}
diff --git a/src/output.c b/src/output.c
index cd7299b1..0eee6331 100644
--- a/src/output.c
+++ b/src/output.c
@@ -32,14 +32,6 @@
 #include "view.h"
 #include "xwayland.h"
 
-static unsigned int
-get_tearing_retry_count(struct output *output)
-{
-	/* Two seconds worth of frames, guessing 60Hz if refresh is invalid */
-	int refresh = output->wlr_output->refresh;
-	return refresh > 0 ? refresh / 500 : 120;
-}
-
 bool
 output_get_tearing_allowance(struct output *output)
 {
@@ -57,11 +49,6 @@ output_get_tearing_allowance(struct output *output)
 		return false;
 	}
 
-	/* tearing should not have failed too many times */
-	if (output->nr_tearing_failures >= get_tearing_retry_count(output)) {
-		return false;
-	}
-
 	/* allow tearing for any window when requested or forced */
 	if (rc.allow_tearing == LAB_TEARING_ENABLED) {
 		if (view->force_tearing == LAB_STATE_UNSPECIFIED) {
@@ -154,22 +141,7 @@ output_frame_notify(struct wl_listener *listener, void *data)
 
 		pending->tearing_page_flip = output_get_tearing_allowance(output);
 
-		bool committed =
-			lab_wlr_scene_output_commit(scene_output, pending);
-
-		if (pending->tearing_page_flip) {
-			if (committed) {
-				output->nr_tearing_failures = 0;
-			} else {
-				if (++output->nr_tearing_failures >=
-						get_tearing_retry_count(output)) {
-					wlr_log(WLR_INFO, "setting tearing allowance failed "
-						"for two consecutive seconds, disabling");
-				}
-				pending->tearing_page_flip = false;
-				lab_wlr_scene_output_commit(scene_output, pending);
-			}
-		}
+		lab_wlr_scene_output_commit(scene_output, pending);
 	}
 
 	struct timespec now = { 0 };
-- 
2.52.0