From fa2d2a40cec25a07046236aab68f44dea2b2dbe8 Mon Sep 17 00:00:00 2001
From: Lionel DARNIS <lionel@wopr.io>
Date: Fri, 21 Aug 2026 09:54:33 +0200
Subject: [PATCH] session: plafonne les trames pre-rendues par le pilote NVIDIA

Passe __GL_MaxFramesAllowed=1 a cosmic-comp lorsque /proc/driver/nvidia
existe. Sans cela le pilote laisse grossir sa file de trames pre-rendues,
ce qui ajoute de la latence a l'affichage (smithay#1562, cosmic-comp#1179).

La variable n'est ajoutee que sur machine NVIDIA ; ailleurs l'environnement
transmis reste le seul COSMIC_SESSION_SOCK.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 Cargo.lock  | 16 ++++++++--------
 src/comp.rs | 11 ++++++++++-
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index efb8899..33d25c9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1889,14 +1889,6 @@ dependencies = [
 name = "softbuffer"
 version = "0.4.1"
 
-[[patch.unused]]
-name = "cosmic-freedesktop-icons"
-version = "0.4.0"
-
-[[patch.unused]]
-name = "smithay-clipboard"
-version = "0.8.0"
-
 [[patch.unused]]
 name = "dpi"
 version = "0.1.2"
@@ -1944,3 +1936,11 @@ version = "0.31.0-beta.2"
 [[patch.unused]]
 name = "winit-x11"
 version = "0.31.0-beta.2"
+
+[[patch.unused]]
+name = "cosmic-freedesktop-icons"
+version = "0.4.0"
+
+[[patch.unused]]
+name = "smithay-clipboard"
+version = "0.8.0"
diff --git a/src/comp.rs b/src/comp.rs
index 8457d08..47ec37c 100644
--- a/src/comp.rs
+++ b/src/comp.rs
@@ -122,12 +122,21 @@ pub fn run_compositor(
 	Ok(tokio::spawn(async move {
 		// Create a new process handler for cosmic-comp, with our compositor socket's
 		// file descriptor as the `COSMIC_SESSION_SOCK` environment variable.
+		let mut comp_env = vec![(
+			"COSMIC_SESSION_SOCK".to_string(),
+			comp.as_raw_fd().to_string(),
+		)];
+		// NVIDIA keeps a growing pool of pre-rendered compositor frames
+		// (smithay#1562 / cosmic-comp#1179). Cap it to a single buffer.
+		if std::path::Path::new("/proc/driver/nvidia").exists() {
+			comp_env.push(("__GL_MaxFramesAllowed".to_string(), "1".to_string()));
+		}
 		process_manager
 			.start_process(
 				Process::new()
 					.with_executable(exec)
 					.with_args(args)
-					.with_env([("COSMIC_SESSION_SOCK", comp.as_raw_fd().to_string())])
+					.with_env(comp_env)
 					.with_on_exit(move |pman, _, err_code, _will_restart| {
 						let session_dbus_tx = session_dbus_tx.clone();
 						async move {