On Tue, Nov 13, 2018 at 03:21:48PM -0800, Matt Roper wrote:
> Some display controllers can be programmed to present non-black colors
> for pixels not covered by any plane (or pixels covered by the
> transparent regions of higher planes). Compositors that want a UI with
> a solid color background can potentially save memory bandwidth by
> setting the CRTC background property and using smaller planes to display
> the rest of the content.
>
> To avoid confusion between different ways of encoding RGB data, we
> define a standard 64-bit format that should be used for this property's
> value. Helper functions and macros are provided to generate and dissect
> values in this standard format with varying component precision values.
>
> v2:
> - Swap internal representation's blue and red bits to make it easier
> to read if printed out. (Ville)
> - Document bgcolor property in drm_blend.c. (Sean Paul)
> - s/background_color/bgcolor/ for consistency between property name and
> value storage field. (Sean Paul)
> - Add a convenience function to attach property to a given crtc.
>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: wei.c.li@xxxxxxxxx
> Cc: harish.krupo.kps@xxxxxxxxx
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Sean Paul <sean@xxxxxxxxxx>
> Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_atomic_state_helper.c | 1 +
> drivers/gpu/drm/drm_atomic_uapi.c | 5 +++++
> drivers/gpu/drm/drm_blend.c | 21 ++++++++++++++++++---
> drivers/gpu/drm/drm_mode_config.c | 6 ++++++
> include/drm/drm_blend.h | 1 +
> include/drm/drm_crtc.h | 17 +++++++++++++++++
> include/drm/drm_mode_config.h | 5 +++++
> include/uapi/drm/drm_mode.h | 26 ++++++++++++++++++++++++++
> 8 files changed, 79 insertions(+), 3 deletions(-)
/snip
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index d3e0fe31efc5..7c4f902aa290 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -888,6 +888,32 @@ struct drm_mode_revoke_lease {
> __u32 lessee_id;
> };
>
> +/*
> + * Put RGBA values into a standard 64-bit representation that can be used
> + * for ioctl parameters, inter-driver commmunication, etc. If the component
> + * values being provided contain less than 16 bits of precision, they'll
> + * be shifted into the most significant bits.
> + */
> +static inline __u64
> +drm_rgba(__u8 bpc, __u16 red, __u16 green, __u16 blue, __u16 alpha)
> +{
> + int msb_shift = 16 - bpc;
> +
> + return (__u64)alpha << msb_shift << 48 |
> + (__u64)red << msb_shift << 32 |
> + (__u64)green << msb_shift << 16 |
> + (__u64)blue << msb_shift;
> +}
> +
> +/*
> + * Extract the specified number of bits of a specific color component from a
> + * standard 64-bit RGBA value.
> + */
> +#define DRM_RGBA_BLUE(c, numbits) (__u16)((c & 0xFFFFull) >> (16-numbits))
> +#define DRM_RGBA_GREEN(c, numbits) (__u16)((c & 0xFFFFull<<16) >> (32-numbits))
> +#define DRM_RGBA_RED(c, numbits) (__u16)((c & 0xFFFFull<<32) >> (48-numbits))
> +#define DRM_RGBA_ALPHA(c, numbits) (__u16)((c & 0xFFFFull<<48) >> (64-numbits))
#define DRM_RGBA_COMP(c, shift, numbits) \
(__u16)(((c) & 0xFFFFull << (shift)) >> (32 - ((shift) + 16 - (numbits)))
#define DRM_RGBA_BLUE(c, numbits) DRM_RGBA_COMP(c, 0, numbits)
#define DRM_RGBA_GREEN(c, numbits) DRM_RGBA_COMP(c, 16, numbits)
#define DRM_RGBA_RED(c, numbits) DRM_RGBA_COMP(c, 32, numbits)
#define DRM_RGBA_ALPHA(c, numbits) DRM_RGBA_COMP(c, 48, numbits)
With that,
Reviewed-by: Sean Paul <sean@xxxxxxxxxx>
> +
> #if defined(__cplusplus)
> }
> #endif
> --
> 2.14.4
>
--
Sean Paul, Software Engineer, Google / Chromium OS
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