Hi Tomi,
Thank you for the patch.
On Fri, Dec 11, 2020 at 01:42:37PM +0200, Tomi Valkeinen wrote:
> The DRM core handles legacy gamma-set ioctl by setting GAMMA_LUT and
> clearing CTM and DEGAMMA_LUT.
>
> This works fine on HW where we have either:
>
> degamma -> ctm -> gamma -> out
>
> or
>
> ctm -> gamma -> out
>
> However, if the HW has gamma table before ctm, the atomic property
> should be DEGAMMA_LUT, and thus we have:
>
> degamma -> ctm -> out
>
> This is fine for userspace which sets gamma table using the properties,
> as the userspace can check for the existence of gamma & degamma, but the
> legacy gamma-set ioctl does not work.
>
> Change the DRM core to use DEGAMMA_LUT instead of GAMMA_LUT when the
> latter is unavailable.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_color_mgmt.c | 22 ++++++++++++++++++----
> drivers/gpu/drm/drm_fb_helper.c | 5 +++++
> 2 files changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
> index 65eb36dc92bf..9100aac1570c 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -91,7 +91,7 @@
> *
> * There is also support for a legacy gamma table, which is set up by calling
> * drm_mode_crtc_set_gamma_size(). The DRM core will then alias the legacy gamma
> - * ramp with "GAMMA_LUT".
> + * ramp with "GAMMA_LUT" or, if that is unavailable, "DEGAMMA_LUT".
> *
> * Support for different non RGB color encodings is controlled through
> * &drm_plane specific COLOR_ENCODING and COLOR_RANGE properties. They
> @@ -238,6 +238,7 @@ EXPORT_SYMBOL(drm_mode_crtc_set_gamma_size);
> static bool drm_crtc_supports_legacy_gamma(struct drm_crtc *crtc)
> {
> uint32_t gamma_id = crtc->dev->mode_config.gamma_lut_property->base.id;
> + uint32_t degamma_id = crtc->dev->mode_config.degamma_lut_property->base.id;
>
> if (!crtc->gamma_size)
> return false;
> @@ -245,7 +246,8 @@ static bool drm_crtc_supports_legacy_gamma(struct drm_crtc *crtc)
> if (crtc->funcs->gamma_set)
> return true;
>
> - return !!drm_mode_obj_find_prop_id(&crtc->base, gamma_id);
> + return !!(drm_mode_obj_find_prop_id(&crtc->base, gamma_id) ||
> + drm_mode_obj_find_prop_id(&crtc->base, degamma_id));
> }
>
> /**
> @@ -276,12 +278,22 @@ static int drm_crtc_legacy_gamma_set(struct drm_crtc *crtc,
> struct drm_crtc_state *crtc_state;
> struct drm_property_blob *blob;
> struct drm_color_lut *blob_data;
> + uint32_t gamma_id = dev->mode_config.gamma_lut_property->base.id;
> + uint32_t degamma_id = dev->mode_config.degamma_lut_property->base.id;
> + bool use_gamma_lut;
> int i, ret = 0;
> bool replaced;
>
> if (crtc->funcs->gamma_set)
> return crtc->funcs->gamma_set(crtc, red, green, blue, size, ctx);
>
> + if (drm_mode_obj_find_prop_id(&crtc->base, gamma_id))
> + use_gamma_lut = true;
> + else if (drm_mode_obj_find_prop_id(&crtc->base, degamma_id))
> + use_gamma_lut = false;
> + else
> + return -ENODEV;
> +
> state = drm_atomic_state_alloc(crtc->dev);
> if (!state)
> return -ENOMEM;
> @@ -311,9 +323,11 @@ static int drm_crtc_legacy_gamma_set(struct drm_crtc *crtc,
> }
>
> /* Set GAMMA_LUT and reset DEGAMMA_LUT and CTM */
> - replaced = drm_property_replace_blob(&crtc_state->degamma_lut, NULL);
> + replaced = drm_property_replace_blob(&crtc_state->degamma_lut,
> + use_gamma_lut ? NULL : blob);
> replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
> - replaced |= drm_property_replace_blob(&crtc_state->gamma_lut, blob);
> + replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
> + use_gamma_lut ? blob : NULL);
> crtc_state->color_mgmt_changed |= replaced;
>
> ret = drm_atomic_commit(state);
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index e82db0f4e771..5ad19785daee 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -1059,6 +1059,11 @@ static int setcmap_atomic(struct fb_cmap *cmap, struct fb_info *info)
> goto out_state;
> }
>
> + /*
> + * FIXME: This always uses gamma_lut. Some HW have only
> + * degamma_lut, in which case we should reset gamma_lut and set
> + * degamma_lut. See drm_crtc_legacy_gamma_set().
> + */
> replaced = drm_property_replace_blob(&crtc_state->degamma_lut,
> NULL);
> replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
--
Regards,
Laurent Pinchart
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