On Tue, 1 Jun 2021 16:11:27 +0530
Uma Shankar <uma.shankar@xxxxxxxxx> wrote:
> Add a gamma mode property to enable various kind of
> gamma modes supported by platforms like: Interpolated, Split,
> Multi Segmented, Logarithmic etc. Userspace can get this property
> and should be able to get the platform capabilities wrt various
> gamma modes possible and the possible ranges.
>
> It can select one of the modes exposed as blob_id as an
> enum and set the respective mode.
>
> It can then create the LUT and send it to driver using
> already available GAMMA_LUT property as blob.
>
> Note: This is based on design by Ville and is being carried forward
> based on his original idea.
>
> Signed-off-by: Uma Shankar <uma.shankar@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_atomic_uapi.c | 5 +++
> drivers/gpu/drm/drm_color_mgmt.c | 75 +++++++++++++++++++++++++++++++
> include/drm/drm_color_mgmt.h | 8 ++++
> include/drm/drm_crtc.h | 14 ++++++
> include/uapi/drm/drm_mode.h | 43 ++++++++++++++++++
> 5 files changed, 145 insertions(+)
>
...
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 13eeba2a750a..b1eead03ebe8 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -262,6 +262,13 @@ struct drm_crtc_state {
> */
> struct drm_property_blob *mode_blob;
>
> + /**
> + * @gamma_mode: This is a blob_id and exposes the platform capabilities
> + * wrt to various gamma modes and the respective lut ranges. This also
> + * helps user select a gamma mode amongst the supported ones.
> + */
> + u32 gamma_mode;
> +
> /**
> * @degamma_lut:
> *
> @@ -1096,6 +1103,13 @@ struct drm_crtc {
> */
> struct drm_property *scaling_filter_property;
>
> + /**
> + * @gamma_mode_property: Optional CRTC property to enumerate and
> + * select the mode of the crtc gamma/degmama LUTs. This also exposes
> + * the lut ranges of the various supported gamma modes to userspace.
> + */
> + struct drm_property *gamma_mode_property;
> +
> /**
> * @state:
> *
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index 9b6722d45f36..d7758d351936 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -819,6 +819,49 @@ struct hdr_output_metadata {
> };
> };
>
> +/*
> + * DRM_MODE_LUT_GAMMA|DRM_MODE_LUT_DEGAMMA is legal and means the LUT
> + * can be used for either purpose, but not simultaneously. To expose
> + * modes that support gamma and degamma simultaneously the gamma mode
> + * must declare distinct DRM_MODE_LUT_GAMMA and DRM_MODE_LUT_DEGAMMA
> + * ranges.
> + */
> +/* LUT is for gamma (after CTM) */
> +#define DRM_MODE_LUT_GAMMA BIT(0)
> +/* LUT is for degamma (before CTM) */
> +#define DRM_MODE_LUT_DEGAMMA BIT(1)
> +/* linearly interpolate between the points */
> +#define DRM_MODE_LUT_INTERPOLATE BIT(2)
> +/*
> + * the last value of the previous range is the
> + * first value of the current range.
> + */
> +#define DRM_MODE_LUT_REUSE_LAST BIT(3)
> +/* the curve must be non-decreasing */
> +#define DRM_MODE_LUT_NON_DECREASING BIT(4)
> +/* the curve is reflected across origin for negative inputs */
> +#define DRM_MODE_LUT_REFLECT_NEGATIVE BIT(5)
> +/* the same curve (red) is used for blue and green channels as well */
> +#define DRM_MODE_LUT_SINGLE_CHANNEL BIT(6)
> +
> +struct drm_color_lut_range {
> + /* DRM_MODE_LUT_* */
> + __u32 flags;
> + /* number of points on the curve */
> + __u16 count;
> + /* input/output bits per component */
> + __u8 input_bpc, output_bpc;
> + /* input start/end values */
> + __s32 start, end;
> + /* output min/max values */
> + __s32 min, max;
> +};
> +
> +enum lut_type {
> + LUT_TYPE_DEGAMMA = 0,
> + LUT_TYPE_GAMMA = 1,
> +};
> +
> #define DRM_MODE_PAGE_FLIP_EVENT 0x01
> #define DRM_MODE_PAGE_FLIP_ASYNC 0x02
> #define DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE 0x4
Hi,
where is the UAPI documentation for this new GAMMA_MODE?
As a userspace dev, I have no idea what to do with the above based on
what's written here.
Also, reading the description of DRM_CLIENT_CAP_ADVANCE_GAMMA_MODES in
patch 5/9, what difference does it make whether userspace sets or does
not set that cap? I don't understand the implications from the
description.
Thanks,
pq
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