drm: Add drm_format_{horz, vert}_chroma_subsampling() utility functions

These functions return the chroma subsampling factors for the specified
pixel format.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Pauli Nieminen <pauli.nieminen@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 5cc1d2d..9f536d6 100644 (file)
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -1107,3 +1107,57 @@ int drm_format_plane_cpp(uint32_t format, int plane)
        }
 }
 EXPORT_SYMBOL(drm_format_plane_cpp);
+
+/**
+ * drm_format_horz_chroma_subsampling - get the horizontal chroma subsampling factor
+ * @format: pixel format (DRM_FORMAT_*)
+ *
+ * RETURNS:
+ * The horizontal chroma subsampling factor for the
+ * specified pixel format.
+ */
+int drm_format_horz_chroma_subsampling(uint32_t format)
+{
+       switch (format) {
+       case DRM_FORMAT_YUV411:
+       case DRM_FORMAT_YUV410:
+               return 4;
+       case DRM_FORMAT_YUYV:
+       case DRM_FORMAT_YVYU:
+       case DRM_FORMAT_UYVY:
+       case DRM_FORMAT_VYUY:
+       case DRM_FORMAT_NV12:
+       case DRM_FORMAT_NV21:
+       case DRM_FORMAT_NV16:
+       case DRM_FORMAT_NV61:
+       case DRM_FORMAT_YUV422:
+       case DRM_FORMAT_YUV420:
+               return 2;
+       default:
+               return 1;
+       }
+}
+EXPORT_SYMBOL(drm_format_horz_chroma_subsampling);
+
+/**
+ * drm_format_vert_chroma_subsampling - get the vertical chroma subsampling factor
+ * @format: pixel format (DRM_FORMAT_*)
+ *
+ * RETURNS:
+ * The vertical chroma subsampling factor for the
+ * specified pixel format.
+ */
+int drm_format_vert_chroma_subsampling(uint32_t format)
+{
+       switch (format) {
+       case DRM_FORMAT_YUV410:
+               return 4;
+       case DRM_FORMAT_YUV420:
+       case DRM_FORMAT_NV12:
+       case DRM_FORMAT_NV21:
+               return 2;
+       default:
+               return 1;
+       }
+}
+EXPORT_SYMBOL(drm_format_vert_chroma_subsampling);

diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index 9996643..25d46b8 100644 (file)
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -149,5 +149,7 @@ extern void drm_kms_helper_poll_enable(struct drm_device *dev);
 
 extern int drm_format_num_planes(uint32_t format);
 extern int drm_format_plane_cpp(uint32_t format, int plane);
+extern int drm_format_horz_chroma_subsampling(uint32_t format);
+extern int drm_format_vert_chroma_subsampling(uint32_t format);
 
 #endif