On Mon,  7 Mar 2022 21:52:40 +0100
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> Introduce fourcc codes for color-indexed frame buffer formats with two,
> four, and sixteen colors, and provide a mapping from bit per pixel and
> depth to fourcc codes.
> 
> As the number of bits per pixel is less than eight, these rely on proper
> block handling for the calculation of bits per pixel and pitch.
> 
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
> v2:
>   - Improve pixel descriptions,
>   - Require depth to match bpp in drm_mode_legacy_fb_format(),
>   - Set .is_color_indexed flag.
> ---
>  drivers/gpu/drm/drm_fourcc.c  | 21 +++++++++++++++++++++
>  include/uapi/drm/drm_fourcc.h |  5 ++++-
>  2 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index 6c76bd821d17e7c7..29f4fe199c4ddcf0 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -43,6 +43,21 @@ uint32_t drm_mode_legacy_fb_format(uint32_t bpp, uint32_t depth)
>  	uint32_t fmt = DRM_FORMAT_INVALID;
>  
>  	switch (bpp) {
> +	case 1:
> +		if (depth == 1)
> +			fmt = DRM_FORMAT_C1;
> +		break;
> +
> +	case 2:
> +		if (depth == 2)
> +			fmt = DRM_FORMAT_C2;
> +		break;
> +
> +	case 4:
> +		if (depth == 4)
> +			fmt = DRM_FORMAT_C4;
> +		break;
> +
>  	case 8:
>  		if (depth == 8)
>  			fmt = DRM_FORMAT_C8;
> @@ -132,6 +147,12 @@ EXPORT_SYMBOL(drm_driver_legacy_fb_format);
>  const struct drm_format_info *__drm_format_info(u32 format)
>  {
>  	static const struct drm_format_info formats[] = {
> +		{ .format = DRM_FORMAT_C1,		.depth = 1,  .num_planes = 1,
> +		  .char_per_block = { 1, }, .block_w = { 8, }, .block_h = { 1, }, .hsub = 1, .vsub = 1, .is_color_indexed = true },
> +		{ .format = DRM_FORMAT_C2,		.depth = 2,  .num_planes = 1,
> +		  .char_per_block = { 1, }, .block_w = { 4, }, .block_h = { 1, }, .hsub = 1, .vsub = 1, .is_color_indexed = true },
> +		{ .format = DRM_FORMAT_C4,		.depth = 4,  .num_planes = 1,
> +		  .char_per_block = { 1, }, .block_w = { 2, }, .block_h = { 1, }, .hsub = 1, .vsub = 1, .is_color_indexed = true },
>  		{ .format = DRM_FORMAT_C8,		.depth = 8,  .num_planes = 1, .cpp = { 1, 0, 0 }, .hsub = 1, .vsub = 1, .is_color_indexed = true },
>  		{ .format = DRM_FORMAT_R8,		.depth = 8,  .num_planes = 1, .cpp = { 1, 0, 0 }, .hsub = 1, .vsub = 1 },
>  		{ .format = DRM_FORMAT_R10,		.depth = 10, .num_planes = 1, .cpp = { 2, 0, 0 }, .hsub = 1, .vsub = 1 },
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index fc0c1454d2757d5d..457ed39cc48f08e1 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -99,7 +99,10 @@ extern "C" {
>  #define DRM_FORMAT_INVALID	0
>  
>  /* color index */
> -#define DRM_FORMAT_C8		fourcc_code('C', '8', ' ', ' ') /* [7:0] C */
> +#define DRM_FORMAT_C1		fourcc_code('C', '1', ' ', ' ') /* [7:0] C0:C1:C2:C3:C4:C5:C6:C7 1:1:1:1:1:1:1:1 eight pixels/byte */
> +#define DRM_FORMAT_C2		fourcc_code('C', '2', ' ', ' ') /* [7:0] C0:C1:C2:C3 2:2:2:2 four pixels/byte */
> +#define DRM_FORMAT_C4		fourcc_code('C', '4', ' ', ' ') /* [7:0] C0:C1 4:4 two pixels/byte */
> +#define DRM_FORMAT_C8		fourcc_code('C', '8', ' ', ' ') /* [7:0] C 8 one pixel/byte */
>  
>  /* 8 bpp Red */
>  #define DRM_FORMAT_R8		fourcc_code('R', '8', ' ', ' ') /* [7:0] R */

Hi Geert,

this patch looks good to me, so

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.com>


Thanks,
pq