drm: Add drm_format_plane_cpp() utility function

This function returns the bytes per pixel value based on the pixel
format and plane index.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 32ab669f4aed..2c4e9cf2a1d2 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -3498,3 +3498,48 @@ int drm_format_num_planes(uint32_t format)
         }
 }
 EXPORT_SYMBOL(drm_format_num_planes);
+
+/**
+ * drm_format_plane_cpp - determine the bytes per pixel value
+ * @format: pixel format (DRM_FORMAT_*)
+ * @plane: plane index
+ *
+ * RETURNS:
+ * The bytes per pixel value for the specified plane.
+ */
+int drm_format_plane_cpp(uint32_t format, int plane)
+{
+        unsigned int depth;
+        int bpp;
+
+        if (plane >= drm_format_num_planes(format))
+                return 0;
+
+        switch (format) {
+        case DRM_FORMAT_YUYV:
+        case DRM_FORMAT_YVYU:
+        case DRM_FORMAT_UYVY:
+        case DRM_FORMAT_VYUY:
+                return 2;
+        case DRM_FORMAT_NV12:
+        case DRM_FORMAT_NV21:
+        case DRM_FORMAT_NV16:
+        case DRM_FORMAT_NV61:
+                return plane ? 2 : 1;
+        case DRM_FORMAT_YUV410:
+        case DRM_FORMAT_YVU410:
+        case DRM_FORMAT_YUV411:
+        case DRM_FORMAT_YVU411:
+        case DRM_FORMAT_YUV420:
+        case DRM_FORMAT_YVU420:
+        case DRM_FORMAT_YUV422:
+        case DRM_FORMAT_YVU422:
+        case DRM_FORMAT_YUV444:
+        case DRM_FORMAT_YVU444:
+                return 1;
+        default:
+                drm_fb_get_bpp_depth(format, &depth, &bpp);
+                return bpp >> 3;
+        }
+}
+EXPORT_SYMBOL(drm_format_plane_cpp);