Add support for FB Renderer Format DrmFourcc(BA24) in LinuxKMS

As suggested in #9862 this PR adds support for FB Renderer Format DrmFourcc(BA24) in LinuxKMS.

Changelog: Added support for FB Renderer Format DrmFourcc(BA24) in LinuxKMS
Closes #9862

Author: sandreas

internal/backends/linuxkms/renderer/sw.rs

@@ -22,7 +22,7 @@ const SOFTWARE_RENDER_SUPPORTED_DRM_FOURCC_FORMATS: &[drm::buffer::DrmFourcc] =
     // Preferred formats
     drm::buffer::DrmFourcc::Xrgb8888,
     drm::buffer::DrmFourcc::Argb8888,
-    // drm::buffer::DrmFourcc::Bgra8888,
+    drm::buffer::DrmFourcc::Bgra8888,
     // drm::buffer::DrmFourcc::Rgba8888,
 
     // 16-bit formats
@@ -61,6 +61,10 @@ const SOFTWARE_RENDER_SUPPORTED_DRM_FOURCC_FORMATS: &[drm::buffer::DrmFourcc] =
 #[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
 struct DumbBufferPixelXrgb888(pub u32);
 
+#[repr(transparent)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+struct DumbBufferPixelBgra8888(pub u32);
+
 impl From<DumbBufferPixelXrgb888> for PremultipliedRgbaColor {
     #[inline]
     fn from(pixel: DumbBufferPixelXrgb888) -> Self {
@@ -86,6 +90,31 @@ impl From<PremultipliedRgbaColor> for DumbBufferPixelXrgb888 {
     }
 }
 
+impl From<DumbBufferPixelBgra8888> for PremultipliedRgbaColor {
+    #[inline]
+    fn from(pixel: DumbBufferPixelBgra8888) -> Self {
+        let v = pixel.0;
+        PremultipliedRgbaColor {
+            red: (v >> 0) as u8,
+            green: (v >> 8) as u8,
+            blue: (v >> 16) as u8,
+            alpha: (v >> 24) as u8,
+        }
+    }
+}
+
+impl From<PremultipliedRgbaColor> for DumbBufferPixelBgra8888 {
+    #[inline]
+    fn from(pixel: PremultipliedRgbaColor) -> Self {
+        Self(
+            (pixel.alpha as u32) << 24
+                | ((pixel.blue as u32) << 16) // B and R swapped
+                | ((pixel.green as u32) << 8)
+                | (pixel.red as u32),
+        )
+    }
+}
+
 impl TargetPixel for DumbBufferPixelXrgb888 {
     fn blend(&mut self, color: PremultipliedRgbaColor) {
         let mut x = PremultipliedRgbaColor::from(*self);
@@ -102,6 +131,20 @@ impl TargetPixel for DumbBufferPixelXrgb888 {
     }
 }
 
+impl TargetPixel for DumbBufferPixelBgra8888 {
+    fn blend(&mut self, color: PremultipliedRgbaColor) {
+        let mut x = PremultipliedRgbaColor::from(*self);
+        x.blend(color);
+        *self = x.into();
+    }
+    fn from_rgb(r: u8, g: u8, b: u8) -> Self {
+        Self(0xff000000 | ((b as u32) << 16) | ((g as u32) << 8) | (r as u32))
+    }
+    fn background() -> Self {
+        Self(0)
+    }
+}
+
 impl SoftwareRendererAdapter {
     pub fn new(
         device_opener: &crate::DeviceOpener,
@@ -165,6 +208,12 @@ impl crate::fullscreenwindowadapter::FullscreenRenderer for SoftwareRendererAdap
                         bytemuck::cast_slice_mut(pixels.as_mut());
                     self.renderer.render(buffer, self.size.width as usize);
                 }
+
+                drm::buffer::DrmFourcc::Bgra8888 => {
+                    let buffer: &mut [DumbBufferPixelBgra8888] =
+                        bytemuck::cast_slice_mut(pixels.as_mut());
+                    self.renderer.render(buffer, self.size.width as usize);
+                }
                 drm::buffer::DrmFourcc::Rgb565 => {
                     let buffer: &mut [i_slint_core::software_renderer::Rgb565Pixel] =
                         bytemuck::cast_slice_mut(pixels.as_mut());