[PATCH v3 01/10] drm/fourcc: Add drm_format_info_bpp() helper

Geert Uytterhoeven
2022-07-08T18:21:19Z

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>
---
v3:
- Add Reviewed-by,

v2:
- Move up.
---
drivers/gpu/drm/drm_fourcc.c | 19 +++++++++++++++++++
include/drm/drm_fourcc.h | 1 +
2 files changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
index 07741b678798b0f1..cf48ea0b2cb70ba8 100644
--- a/drivers/gpu/drm/drm_fourcc.c
+++ b/drivers/gpu/drm/drm_fourcc.c
@@ -370,6 +370,25 @@ 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
diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 22aa64d07c7905e2..3800a7ad7f0cda7a 100644
--- 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);

--
2.25.1