drivers/graphics: Replace KmsObject trait with an enum

The set of possible KMS object types is fixed.

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

@@ -2,13 +2,10 @@ use std::ffi::c_char;
 use std::fmt::Debug;
 use std::sync::Mutex;
 
-use drm_sys::{
-    drm_mode_modeinfo, DRM_MODE_CONNECTOR_Unknown, DRM_MODE_OBJECT_CONNECTOR,
-    DRM_MODE_OBJECT_ENCODER, DRM_MODE_TYPE_PREFERRED,
-};
+use drm_sys::{drm_mode_modeinfo, DRM_MODE_CONNECTOR_Unknown, DRM_MODE_TYPE_PREFERRED};
 use syscall::Result;
 
-use crate::kms::objects::{KmsObject, KmsObjectId, KmsObjects};
+use crate::kms::objects::{KmsObjectId, KmsObjects};
 use crate::GraphicsAdapter;
 
 impl<T: GraphicsAdapter> KmsObjects<T> {
@@ -62,7 +59,7 @@ impl<T: GraphicsAdapter> KmsObjects<T> {
 }
 
 #[derive(Debug)]
-pub struct KmsConnector<T: Debug + 'static> {
+pub struct KmsConnector<T: Debug> {
     pub encoder_id: KmsObjectId,
     pub modes: Vec<drm_mode_modeinfo>,
     pub connector_type: u32,
@@ -74,7 +71,7 @@ pub struct KmsConnector<T: Debug + 'static> {
     pub driver_data: T,
 }
 
-impl<T: Debug + 'static> KmsConnector<T> {
+impl<T: Debug> KmsConnector<T> {
     pub fn update_from_size(&mut self, width: u32, height: u32) {
         self.modes = vec![Self::modeinfo_for_size(width, height)];
     }
@@ -175,12 +172,6 @@ pub enum DrmSubpixelOrder {
     None,
 }
 
-impl<T: Debug + 'static> KmsObject for Mutex<KmsConnector<T>> {
-    fn object_type(&self) -> u32 {
-        DRM_MODE_OBJECT_CONNECTOR
-    }
-}
-
 // FIXME can we represent connector and encoder using a single struct?
 #[derive(Debug)]
 pub struct KmsEncoder {
@@ -188,9 +179,3 @@ pub struct KmsEncoder {
     pub possible_crtcs: u32,
     pub possible_clones: u32,
 }
-
-impl KmsObject for KmsEncoder {
-    fn object_type(&self) -> u32 {
-        DRM_MODE_OBJECT_ENCODER
-    }
-}

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

@@ -1,11 +1,16 @@
-use std::any::Any;
 use std::collections::HashMap;
 use std::fmt::Debug;
 use std::marker::PhantomData;
 use std::sync::{Arc, Mutex};
 
+use drm_sys::{
+    DRM_MODE_OBJECT_BLOB, DRM_MODE_OBJECT_CONNECTOR, DRM_MODE_OBJECT_ENCODER,
+    DRM_MODE_OBJECT_PROPERTY,
+};
 use syscall::{Error, Result, EINVAL};
 
+use crate::kms::connector::{KmsConnector, KmsEncoder};
+use crate::kms::properties::{KmsBlob, KmsProperty};
 use crate::GraphicsAdapter;
 
 #[derive(Debug)]
@@ -13,7 +18,7 @@ pub struct KmsObjects<T: GraphicsAdapter> {
     next_id: KmsObjectId,
     pub(crate) connectors: Vec<KmsObjectId>,
     pub(crate) encoders: Vec<KmsObjectId>,
-    pub(crate) objects: HashMap<KmsObjectId, Arc<KmsObjectData>>,
+    pub(crate) objects: HashMap<KmsObjectId, Arc<KmsObjectData<T>>>,
     _marker: PhantomData<T>,
 }
 
@@ -28,12 +33,12 @@ impl<T: GraphicsAdapter> KmsObjects<T> {
         }
     }
 
-    pub(crate) fn add<U: KmsObject>(&mut self, data: U) -> KmsObjectId {
+    pub(crate) fn add<U: Into<KmsObjectKind<T>>>(&mut self, data: U) -> KmsObjectId {
         let id = self.next_id;
         self.objects.insert(
             id,
             Arc::new(KmsObjectData {
-                kind: Box::new(data),
+                kind: Box::new(data.into()),
                 properties: Mutex::new(vec![]),
             }),
         );
@@ -42,9 +47,12 @@ impl<T: GraphicsAdapter> KmsObjects<T> {
         id
     }
 
-    pub(crate) fn get<U: KmsObject>(&self, id: KmsObjectId) -> Result<&U> {
+    pub(crate) fn get<'a, U: 'a>(&'a self, id: KmsObjectId) -> Result<&'a U>
+    where
+        &'a U: TryFrom<&'a KmsObjectKind<T>>,
+    {
         let object = self.objects.get(&id).ok_or(Error::new(EINVAL))?;
-        if let Some(object) = (&*object.kind as &dyn Any).downcast_ref::<U>() {
+        if let Ok(object) = (&*object.kind).try_into() {
             Ok(object)
         } else {
             Err(Error::new(EINVAL))
@@ -71,11 +79,53 @@ impl From<KmsObjectId> for u64 {
 }
 
 #[derive(Debug)]
-pub(crate) struct KmsObjectData {
-    kind: Box<dyn KmsObject + 'static>,
+pub(crate) struct KmsObjectData<T: GraphicsAdapter> {
+    kind: Box<KmsObjectKind<T>>,
     pub(crate) properties: Mutex<Vec<(KmsObjectId, u64)>>,
 }
 
-pub trait KmsObject: Any + Debug {
-    fn object_type(&self) -> u32;
+macro_rules! define_object_kinds {
+    (<$T:ident> $(
+        $variant:ident($data:ty) = $type:ident,
+    )*) => {
+        #[derive(Debug)]
+        pub(crate) enum KmsObjectKind<$T: GraphicsAdapter> {
+            $($variant($data),)*
+        }
+
+        impl<$T: GraphicsAdapter> KmsObjectKind<$T> {
+            fn object_type(&self) -> u32 {
+                match self {
+                    $(Self::$variant(_) => $type,)*
+                }
+            }
+        }
+
+
+        $(
+            impl<$T: GraphicsAdapter> From<$data> for KmsObjectKind<$T> {
+                fn from(value: $data) -> Self {
+                    Self::$variant(value)
+                }
+            }
+
+            impl<'a, $T: GraphicsAdapter> TryFrom<&'a KmsObjectKind<$T>> for &'a $data {
+                type Error = ();
+
+                fn try_from(value: &'a KmsObjectKind<T>) -> Result<Self, Self::Error> {
+                    match value {
+                        KmsObjectKind::$variant(data) => Ok(data),
+                        _ => Err(()),
+                    }
+                }
+            }
+        )*
+    };
+}
+
+define_object_kinds! { <T>
+    Connector(Mutex<KmsConnector<T::Connector>>) = DRM_MODE_OBJECT_CONNECTOR,
+    Encoder(KmsEncoder) = DRM_MODE_OBJECT_ENCODER,
+    Property(KmsProperty) = DRM_MODE_OBJECT_PROPERTY,
+    Blob(KmsBlob) = DRM_MODE_OBJECT_BLOB,
 }

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

@@ -2,10 +2,10 @@ use std::ffi::c_char;
 use std::fmt::Debug;
 use std::sync::Mutex;
 
-use drm_sys::{DRM_MODE_OBJECT_BLOB, DRM_MODE_OBJECT_PROPERTY, DRM_PROP_NAME_LEN};
+use drm_sys::DRM_PROP_NAME_LEN;
 use syscall::{Error, Result, EINVAL};
 
-use crate::kms::objects::{KmsObject, KmsObjectId, KmsObjects};
+use crate::kms::objects::{KmsObjectId, KmsObjects};
 use crate::GraphicsAdapter;
 
 impl<T: GraphicsAdapter> KmsObjects<T> {
@@ -111,19 +111,7 @@ pub enum KmsPropertyKind {
     SignedRange(i64, i64),
 }
 
-impl KmsObject for KmsProperty {
-    fn object_type(&self) -> u32 {
-        DRM_MODE_OBJECT_PROPERTY
-    }
-}
-
 #[derive(Debug)]
 pub struct KmsBlob {
     data: Vec<u8>,
 }
-
-impl KmsObject for KmsBlob {
-    fn object_type(&self) -> u32 {
-        DRM_MODE_OBJECT_BLOB
-    }
-}

drivers/graphics/driver-graphics/src/lib.rs

@@ -36,7 +36,7 @@ pub struct StandardProperties {
 }
 
 pub trait GraphicsAdapter: Sized + Debug {
-    type Connector: Debug + 'static;
+    type Connector: Debug;
 
     type Buffer: Buffer;