drm/fourcc: Add drm_format_info_bpp() helper

Add a helper to retrieve the actual number of bits per pixel for a
plane, taking into account the number of characters and pixels per
block for tiled formats.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1cae5ebc28513ec1c91c66b00647ce3ca23bfba7.1657294931.git.geert@linux-m68k.org

diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
index 07741b6..cf48ea0 100644 (file)
--- a/drivers/gpu/drm/drm_fourcc.c
+++ b/drivers/gpu/drm/drm_fourcc.c
@@ -371,6 +371,25 @@ unsigned int drm_format_info_block_height(const struct drm_format_info *info,
 EXPORT_SYMBOL(drm_format_info_block_height);
 
 /**
+ * drm_format_info_bpp - number of bits per pixel
+ * @info: pixel format info
+ * @plane: plane index
+ *
+ * Returns:
+ * The actual number of bits per pixel, depending on the plane index.
+ */
+unsigned int drm_format_info_bpp(const struct drm_format_info *info, int plane)
+{
+       if (!info || plane < 0 || plane >= info->num_planes)
+               return 0;
+
+       return info->char_per_block[plane] * 8 /
+              (drm_format_info_block_width(info, plane) *
+               drm_format_info_block_height(info, plane));
+}
+EXPORT_SYMBOL(drm_format_info_bpp);
+
+/**
  * drm_format_info_min_pitch - computes the minimum required pitch in bytes
  * @info: pixel format info
  * @plane: plane index

diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 22aa64d..3800a7a 100644 (file)
--- a/include/drm/drm_fourcc.h
+++ b/include/drm/drm_fourcc.h
@@ -313,6 +313,7 @@ unsigned int drm_format_info_block_width(const struct drm_format_info *info,
                                         int plane);
 unsigned int drm_format_info_block_height(const struct drm_format_info *info,
                                          int plane);
+unsigned int drm_format_info_bpp(const struct drm_format_info *info, int plane);
 uint64_t drm_format_info_min_pitch(const struct drm_format_info *info,
                                   int plane, unsigned int buffer_width);