drivers/graphics/driver-graphics: Introduce set_connector_edid helper

And don't create a new blob unless the EDID actually changes.

drivers/graphics/driver-graphics/src/kms/connector.rs

@@ -68,6 +68,23 @@ impl<T: GraphicsAdapter> KmsObjects<T> {
         self.get(id)
     }
 
+    pub fn set_connector_edid(&mut self, id: KmsObjectId, edid: Vec<u8>) {
+        let mut connector = self.get_connector(id).unwrap().lock().unwrap();
+        connector.update_from_edid(&edid);
+        let old_edid = connector.edid;
+        drop(connector);
+
+        if old_edid != KmsObjectId::INVALID {
+            if self.get_blob(old_edid).unwrap() == edid {
+                return; // EDID is unchanged; nothing to do
+            }
+            self.remove_blob(old_edid).unwrap();
+        }
+
+        let blob = self.add_blob(edid);
+        self.get_connector(id).unwrap().lock().unwrap().edid = blob;
+    }
+
     pub fn encoder_ids(&self) -> &[KmsObjectId] {
         &self.encoders
     }
@@ -142,7 +159,7 @@ impl<T: GraphicsAdapter> KmsConnector<T> {
         self.modes = vec![modeinfo_for_size(width, height)];
     }
 
-    pub fn update_from_edid(&mut self, edid: &[u8]) {
+    fn update_from_edid(&mut self, edid: &[u8]) {
         let edid = edid::parse(edid).unwrap().1;
 
         if let Some(first_detailed_timing) =

drivers/graphics/driver-graphics/src/kms/properties.rs

@@ -80,6 +80,18 @@ impl<T: GraphicsAdapter> KmsObjects<T> {
         self.add(KmsBlob { data })
     }
 
+    pub fn remove_blob(&mut self, id: KmsObjectId) -> Result<()> {
+        let Some(object) = self.objects.get(&id) else {
+            return Err(Error::new(ENOENT));
+        };
+        let KmsObject::Blob(_) = object else {
+            return Err(Error::new(ENOENT));
+        };
+        self.objects.remove(&id).unwrap();
+
+        Ok(())
+    }
+
     pub fn get_blob(&self, id: KmsObjectId) -> Result<&[u8]> {
         Ok(&self.get::<KmsBlob>(id)?.data)
     }

drivers/graphics/virtio-gpud/src/scheme.rs

@@ -395,12 +395,8 @@ impl<'a> GraphicsAdapter for VirtGpuAdapter<'a> {
             };
 
             if self.has_edid {
-                connector.update_from_edid(&display.edid);
-
                 drop(connector);
-
-                let blob = objects.add_blob(display.edid.clone());
-                objects.get_connector(id).unwrap().lock().unwrap().edid = blob;
+                objects.set_connector_edid(id, display.edid.clone());
             } else {
                 connector.update_from_size(display.width, display.height);
             }