driver: choose sgi_video_sync scheduler for NVIDIA

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/backend/driver.c

@@ -19,6 +19,13 @@ void apply_driver_workarounds(struct session *ps, enum driver driver) {
 	}
 }
 
+enum vblank_scheduler_type choose_vblank_scheduler(enum driver driver) {
+	if (driver & DRIVER_INTEL) {
+		return SGI_VIDEO_SYNC_VBLANK_SCHEDULER;
+	}
+	return PRESENT_VBLANK_SCHEDULER;
+}
+
 enum driver detect_driver(xcb_connection_t *c, backend_t *backend_data, xcb_window_t window) {
 	enum driver ret = 0;
 	// First we try doing backend agnostic detection using RANDR

src/backend/driver.h

@@ -7,6 +7,7 @@
 #include <stdio.h>
 #include <xcb/xcb.h>
 
+#include "config.h"
 #include "utils.h"
 
 struct session;
@@ -41,6 +42,8 @@ enum driver detect_driver(xcb_connection_t *, struct backend_base *, xcb_window_
 
 /// Apply driver specified global workarounds. It's safe to call this multiple times.
 void apply_driver_workarounds(struct session *ps, enum driver);
+/// Choose a vblank scheduler based on the driver.
+enum vblank_scheduler_type choose_vblank_scheduler(enum driver driver);
 
 // Print driver names to stdout, for diagnostics
 static inline void print_drivers(enum driver drivers) {

src/config.h

@@ -83,6 +83,14 @@ enum vblank_scheduler_type {
 	LAST_VBLANK_SCHEDULER,
 };
 
+static inline const char *vblank_scheduler_type_str(enum vblank_scheduler_type type) {
+	switch (type) {
+	case PRESENT_VBLANK_SCHEDULER: return "present";
+	case SGI_VIDEO_SYNC_VBLANK_SCHEDULER: return "sgi_video_sync";
+	default: return "invalid";
+	}
+}
+
 /// Internal, private options for debugging and development use.
 struct debug_options {
 	/// Try to reduce frame latency by using vblank interval and render time

src/picom.c

@@ -1485,6 +1485,10 @@ static bool redirect_start(session_t *ps) {
 		ps->frame_pacing = false;
 	}
 
+	// Re-detect driver since we now have a backend
+	ps->drivers = detect_driver(ps->c.c, ps->backend_data, ps->c.screen_info->root);
+	apply_driver_workarounds(ps, ps->drivers);
+
 	if (ps->present_exists && ps->frame_pacing) {
 		// Initialize rendering and frame timing statistics, and frame pacing
 		// states.
@@ -1492,11 +1496,14 @@ static bool redirect_start(session_t *ps) {
 		ps->last_msc = 0;
 		ps->last_schedule_delay = 0;
 		render_statistics_reset(&ps->render_stats);
-		enum vblank_scheduler_type scheduler_type = PRESENT_VBLANK_SCHEDULER;
+		enum vblank_scheduler_type scheduler_type =
+		    choose_vblank_scheduler(ps->drivers);
 		if (ps->o.debug_options.force_vblank_scheduler != LAST_VBLANK_SCHEDULER) {
 			scheduler_type =
 			    (enum vblank_scheduler_type)ps->o.debug_options.force_vblank_scheduler;
 		}
+		log_info("Using vblank scheduler: %s.",
+		         vblank_scheduler_type_str(scheduler_type));
 		ps->vblank_scheduler = vblank_scheduler_new(
 		    ps->loop, &ps->c, session_get_target_window(ps), scheduler_type);
 		if (!ps->vblank_scheduler) {
@@ -1515,10 +1522,6 @@ static bool redirect_start(session_t *ps) {
 	ps->redirected = true;
 	ps->first_frame = true;
 
-	// Re-detect driver since we now have a backend
-	ps->drivers = detect_driver(ps->c.c, ps->backend_data, ps->c.screen_info->root);
-	apply_driver_workarounds(ps, ps->drivers);
-
 	root_damaged(ps);
 
 	// Repaint the whole screen