Move the modifier from add_planar_framebuffer to PlanarBuffer

The modifier is a property of the buffer, so let’s put it where it
belongs.

This adds a validation that the flags correspond to the modifier.
Another option would be to remove the flag and instead rely on whether
the modifier is set or not to set it for the kernel, but I’m not sure
this actually improves anything.

Author: linkmauve

src/buffer/mod.rs

@@ -109,6 +109,8 @@ pub trait PlanarBuffer {
     fn size(&self) -> (u32, u32);
     /// The format of the buffer.
     fn format(&self) -> DrmFourcc;
+    /// The modifier of the buffer.
+    fn modifier(&self) -> Option<DrmModifier>;
     /// The pitches of the buffer.
     fn pitches(&self) -> [u32; 4];
     /// The handles to the buffer.

src/control/mod.rs

@@ -309,21 +309,29 @@ pub trait Device: super::Device {
     fn add_planar_framebuffer<B>(
         &self,
         planar_buffer: &B,
-        modifiers: &[Option<DrmModifier>; 4],
         flags: FbCmd2Flags,
     ) -> Result<framebuffer::Handle, SystemError>
     where
         B: buffer::PlanarBuffer + ?Sized,
     {
+        let modifier = planar_buffer.modifier();
+        let has_modifier = flags.contains(FbCmd2Flags::MODIFIERS);
+        assert!((has_modifier && modifier.is_some()) || (!has_modifier && modifier.is_none()));
+        let modifier = if let Some(modifier) = modifier {
+            u64::from(modifier)
+        } else {
+            0
+        };
+
         let (w, h) = planar_buffer.size();
         let opt_handles = planar_buffer.handles();
 
         let handles = bytemuck::cast(opt_handles);
         let mods = [
-            modifiers[0].map(Into::<u64>::into).unwrap_or(0),
-            modifiers[1].map(Into::<u64>::into).unwrap_or(0),
-            modifiers[2].map(Into::<u64>::into).unwrap_or(0),
-            modifiers[3].map(Into::<u64>::into).unwrap_or(0),
+            opt_handles[0].map_or(0, |_| modifier),
+            opt_handles[1].map_or(0, |_| modifier),
+            opt_handles[2].map_or(0, |_| modifier),
+            opt_handles[3].map_or(0, |_| modifier),
         ];
 
         let info = ffi::mode::add_fb2(