backends/native: Add support to disable VRR using udev

This can be used to disable VRR in specific drivers and hardware
combinations where it is found to be problematic.

No default rules are added for now to encourage testing.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1154>

src/backends/native/meta-backend-native.c

@@ -537,6 +537,9 @@ add_drm_device (MetaBackendNative  *backend_native,
   if (meta_is_udev_device_disable_modifiers (device))
     flags |= META_KMS_DEVICE_FLAG_DISABLE_MODIFIERS;
 
+  if (meta_is_udev_device_disable_vrr (device))
+    flags |= META_KMS_DEVICE_FLAG_DISABLE_VRR;
+
   if (meta_is_udev_device_preferred_primary (device))
     flags |= META_KMS_DEVICE_FLAG_PREFERRED_PRIMARY;
 

src/backends/native/meta-kms-types.h

@@ -63,6 +63,7 @@ typedef enum _MetaKmsDeviceFlag
   META_KMS_DEVICE_FLAG_HAS_ADDFB2 = 1 << 5,
   META_KMS_DEVICE_FLAG_FORCE_LEGACY = 1 << 6,
   META_KMS_DEVICE_FLAG_DISABLE_CLIENT_MODIFIERS = 1 << 7,
+  META_KMS_DEVICE_FLAG_DISABLE_VRR = 1 << 8,
 } MetaKmsDeviceFlag;
 
 typedef enum _MetaKmsResourceChanges

src/backends/native/meta-udev.c

@@ -100,6 +100,13 @@ meta_is_udev_device_disable_modifiers (GUdevDevice *device)
                                    "mutter-device-disable-kms-modifiers");
 }
 
+gboolean
+meta_is_udev_device_disable_vrr (GUdevDevice *device)
+{
+  return meta_has_udev_device_tag (device,
+                                   "mutter-device-disable-vrr");
+}
+
 gboolean
 meta_is_udev_device_ignore (GUdevDevice *device)
 {

src/backends/native/meta-udev.h

@@ -32,6 +32,8 @@ gboolean meta_is_udev_device_boot_vga (GUdevDevice *device);
 
 gboolean meta_is_udev_device_disable_modifiers (GUdevDevice *device);
 
+gboolean meta_is_udev_device_disable_vrr (GUdevDevice *device);
+
 gboolean meta_is_udev_device_ignore (GUdevDevice *device);
 
 gboolean meta_is_udev_test_device (GUdevDevice *device);