From 3ad7e030cedc49bf2540ffcd8b1db6c58a058c80 Mon Sep 17 00:00:00 2001
From: stefan11111 <stefan11111@shitposting.expert>
Date: Sun, 15 Mar 2026 12:12:55 +0200
Subject: [PATCH] modesetting: find the first compatible dri device as default

This change replaces the default "/dev/dri/card0" by a loop which
searches for the first compatible device.

This change avoids the error below which happens on some ARM boards:
(EE) No devices detected.
(EE)
Fatal server error:
(EE) no screens found(EE)
(EE)

Signed-off-by: Patrick Lerda <patrick9876@free.fr>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1496>

----------------------------------------------------------------------------

modesetting: Plug seatd suppport into the dynamic dri node detection

Extended dynamic detection to 32 /dev nodes

Signed-off-by: stefan11111 <stefan11111@shitposting.expert>
---
 hw/xfree86/drivers/video/modesetting/driver.c | 55 ++++++++++++++-----
 1 file changed, 40 insertions(+), 15 deletions(-)

diff --git a/hw/xfree86/drivers/video/modesetting/driver.c b/hw/xfree86/drivers/video/modesetting/driver.c
index a10abc48dc..5332fab1ad 100644
--- a/hw/xfree86/drivers/video/modesetting/driver.c
+++ b/hw/xfree86/drivers/video/modesetting/driver.c
@@ -236,6 +236,27 @@ get_passed_fd(void)
     return -1;
 }
 
+static int
+ms_try_open(const char *dev)
+{
+    int fd = -1;
+
+    if (!dev) {
+        return -1;
+    }
+
+    fd = open(dev, O_RDWR | O_CLOEXEC, 0);
+    if (fd >= 0) {
+        return fd;
+    }
+
+#ifdef SEATD_LIBSEAT
+    return seatd_libseat_open_graphics(dev);
+#else
+    return -1;
+#endif
+}
+
 static int
 open_hw(const char *dev)
 {
@@ -245,23 +266,27 @@ open_hw(const char *dev)
         return fd;
 
     if (dev){
-        fd = open(dev, O_RDWR | O_CLOEXEC, 0);
-	#ifdef SEATD_LIBSEAT
-	/* try to open dev node via libseat */
-	if (fd == -1) {
-	    fd = seatd_libseat_open_graphics(dev);
-	}
-	#endif
+        fd = ms_try_open(dev);
     } else {
         dev = getenv("KMSDEVICE");
-        if ((NULL == dev) || ((fd = open(dev, O_RDWR | O_CLOEXEC, 0)) == -1)) {
-            dev = "/dev/dri/card0";
-            fd = open(dev, O_RDWR | O_CLOEXEC, 0);
-	    #ifdef SEATD_LIBSEAT
-	    if (fd == -1){
-                fd = seatd_libseat_open_graphics(dev);
-	    }
-	    #endif
+        if ((NULL == dev) || ((fd = ms_try_open(dev)) < 0)) {
+            int i;
+            char buf[] = "/dev/dri/cardxx";
+
+            for (i = 0; i < 32; i++) {
+                sprintf(buf, "/dev/dri/card%d", i);
+
+                if ((fd = ms_try_open(buf)) >= 0) {
+                    uint64_t check_dumb = 0;
+
+                    if (drmGetCap(fd, DRM_CAP_DUMB_BUFFER, &check_dumb) >= 0 && check_dumb) {
+                        break;
+                    }
+
+                    close(fd);
+                    fd = -1;
+                }
+            }
         }
     }
     if (fd == -1) {