From 65ef0619c8e8415b2a89fbe327844a7e9af88a79 Mon Sep 17 00:00:00 2001
From: Subs <frog2wah@gmail.com>
Date: Thu, 13 Oct 2022 16:21:56 +0200
Subject: [PATCH] [DRM] Use the current resolution

In order to prevent an unnecessary modeswitch and use the current TTY resolution, don't use the preferred mode reported by DRM. This is useful for people who set a custom resolution at boot and are forced into the monitor's preferred resolution when a SFML DRM app starts
---
 extlibs/headers/drm/drm-common.c   | 40 ++++++++----------------------
 src/SFML/Window/DRM/DRMContext.cpp | 20 +++++++++------
 2 files changed, 23 insertions(+), 37 deletions(-)

diff --git a/extlibs/headers/drm/drm-common.c b/extlibs/headers/drm/drm-common.c
index 7fdd422b0..9a870054a 100644
--- a/extlibs/headers/drm/drm-common.c
+++ b/extlibs/headers/drm/drm-common.c
@@ -309,34 +309,6 @@ int init_drm(struct drm *drm, const char *device, const char *mode_str,
 			printf("requested mode not found, using default mode!\n");
 	}
 
-	/* find preferred mode or the highest resolution mode: */
-	if (!drm->mode)
-	{
-		for (i = 0, area = 0; i < connector->count_modes; i++)
-		{
-			drmModeModeInfo *current_mode = &connector->modes[i];
-
-			if (current_mode->type & DRM_MODE_TYPE_PREFERRED)
-			{
-				drm->mode = current_mode;
-				break;
-			}
-
-			int current_area = current_mode->hdisplay * current_mode->vdisplay;
-			if (current_area > area)
-			{
-				drm->mode = current_mode;
-				area = current_area;
-			}
-		}
-	}
-
-	if (!drm->mode)
-	{
-		printf("could not find mode!\n");
-		return -1;
-	}
-
 	/* find encoder: */
 	for (i = 0; i < resources->count_encoders; i++)
 	{
@@ -373,7 +345,17 @@ int init_drm(struct drm *drm, const char *device, const char *mode_str,
     // get original display mode so we can restore display mode after program exits
     drm->original_crtc = drmModeGetCrtc(drm->fd, drm->crtc_id);
 
-	if(getenv("SFML_DRM_DEBUG"))
+	/* Let's use the current mode rather than the preferred one if the user didn't
+	 * specify a mode with env vars
+	 */
+	if (!drm->mode)
+	{
+		if(getenv("SFML_DRM_DEBUG"))
+			printf("DRM using the current mode\n");
+		drm->mode = &(drm->original_crtc->mode);
+	}
+
+	if (getenv("SFML_DRM_DEBUG"))
 	{
 		printf("DRM Mode used: %s@%d\n", drm->mode->name, drm->mode->vrefresh);
 	}
diff --git a/src/SFML/Window/DRM/DRMContext.cpp b/src/SFML/Window/DRM/DRMContext.cpp
index d73409413..d92a10a4e 100644
--- a/src/SFML/Window/DRM/DRMContext.cpp
+++ b/src/SFML/Window/DRM/DRMContext.cpp
@@ -94,14 +94,18 @@ namespace
         if (!initialized)
             return;
 
-        drmModeSetCrtc(drmNode.fd,
-                       drmNode.original_crtc->crtc_id,
-                       drmNode.original_crtc->buffer_id,
-                       drmNode.original_crtc->x,
-                       drmNode.original_crtc->y,
-                       &drmNode.connector_id,
-                       1,
-                       &drmNode.original_crtc->mode);
+        /* Avoid a modeswitch if possible */
+        if (drmNode.mode != &drmNode.original_crtc->mode)
+            drmModeSetCrtc(drmNode.fd,
+                           drmNode.original_crtc->crtc_id,
+                           drmNode.original_crtc->buffer_id,
+                           drmNode.original_crtc->x,
+                           drmNode.original_crtc->y,
+                           &drmNode.connector_id,
+                           1,
+                           &drmNode.original_crtc->mode);
+        else if (getenv("SFML_DRM_DEBUG"))
+            printf("DRM keeping the same mode since using the original one\n");
 
         drmModeFreeConnector(drmNode.saved_connector);
         drmModeFreeEncoder(drmNode.saved_encoder);