[RFC,v2,03/10] drm: fourcc: Add drm_format_plane_width_bytes()

Commit Message

Hyun Kwon Jan. 26, 2018, 2:04 a.m. UTC

drm_format_plane_width_bytes() calculates and returns
the number of bytes for given width of specified format.
The calculation uses the macro pixel information to avoid
bit level rounding.

Signed-off-by: Hyun Kwon <[e-mail]>
---
v2
- This function is added
---
---
 drivers/gpu/drm/drm_fourcc.c | 22 ++++++++++++++++++++++
 include/drm/drm_fourcc.h     |  2 ++
 2 files changed, 24 insertions(+)

Patch

diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
index 8fc1e35..2070276 100644
--- a/drivers/gpu/drm/drm_fourcc.c
+++ b/drivers/gpu/drm/drm_fourcc.c
@@ -376,3 +376,25 @@  int drm_format_plane_height(int height, uint32_t format, int plane)
 	return height / info->vsub;
 }
 EXPORT_SYMBOL(drm_format_plane_height);
+
+/**
+ * drm_format_plane_width_bytes - bytes of the given width of the plane
+ * @info: DRM format information
+ * @plane: plane index
+ * @width: width to get the number of bytes
+ *
+ * Returns:
+ * The bytes of @width of @plane.
+ */
+int drm_format_plane_width_bytes(const struct drm_format_info *info,
+				 int plane, int width)
+{
+	int width_bits;
+
+	if (!info || plane >= info->num_planes)
+		return 0;
+
+	width_bits = DIV_ROUND_UP(width * info->bpm[plane], info->ppm[plane]);
+	return DIV_ROUND_UP(width_bits, 8);
+}
+EXPORT_SYMBOL(drm_format_plane_width_bytes);
diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 64038e9..1eafeb9 100644
--- a/include/drm/drm_fourcc.h
+++ b/include/drm/drm_fourcc.h
@@ -80,6 +80,8 @@  int drm_format_horz_chroma_subsampling(uint32_t format);
 int drm_format_vert_chroma_subsampling(uint32_t format);
 int drm_format_plane_width(int width, uint32_t format, int plane);
 int drm_format_plane_height(int height, uint32_t format, int plane);
+int drm_format_plane_width_bytes(const struct drm_format_info *info,
+				 int plane, int width);
 const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf);
 
 #endif /* __DRM_FOURCC_H__ */