Hi Tomi,

Thank you for the patch.

On Tue, Dec 08, 2020 at 03:57:58PM +0200, Tomi Valkeinen wrote:
> We currently have drm_atomic_helper_legacy_gamma_set() helper which can
> be used to handle legacy gamma-set ioctl.
> drm_atomic_helper_legacy_gamma_set() sets GAMMA_LUT, and clears
> 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.
> 
> This patch fixes the issue by changing
> drm_atomic_helper_legacy_gamma_set() so that GAMMA_LUT will be used if
> it exists, and DEGAMMA_LUT will be used as a fallback.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkei...@ti.com>

Reviewed-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>

> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 15 ++++++++++++---
>  drivers/gpu/drm/drm_color_mgmt.c    |  4 ++++
>  drivers/gpu/drm/drm_fb_helper.c     |  8 ++++++--
>  include/drm/drm_crtc.h              |  3 +++
>  4 files changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c 
> b/drivers/gpu/drm/drm_atomic_helper.c
> index ba1507036f26..117b186fe646 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3512,6 +3512,10 @@ EXPORT_SYMBOL(drm_atomic_helper_page_flip_target);
>   * that support color management through the DEGAMMA_LUT/GAMMA_LUT
>   * properties. See drm_crtc_enable_color_mgmt() and the containing chapter 
> for
>   * how the atomic color management and gamma tables work.
> + *
> + * This function uses the GAMMA_LUT or DEGAMMA_LUT property for the gamma 
> table.
> + * GAMMA_LUT property is used if it exists, and DEGAMMA_LUT property is used 
> as
> + * a fallback.
>   */
>  int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
>                                      u16 *red, u16 *green, u16 *blue,
> @@ -3526,6 +3530,9 @@ int drm_atomic_helper_legacy_gamma_set(struct drm_crtc 
> *crtc,
>       int i, ret = 0;
>       bool replaced;
>  
> +     if (!crtc->has_gamma_prop && !crtc->has_degamma_prop)
> +             return -ENODEV;
> +
>       state = drm_atomic_state_alloc(crtc->dev);
>       if (!state)
>               return -ENOMEM;
> @@ -3554,10 +3561,12 @@ int drm_atomic_helper_legacy_gamma_set(struct 
> drm_crtc *crtc,
>               goto fail;
>       }
>  
> -     /* Reset DEGAMMA_LUT and CTM properties. */
> -     replaced  = drm_property_replace_blob(&crtc_state->degamma_lut, NULL);
> +     /* Set GAMMA/DEGAMMA_LUT and reset DEGAMMA/GAMMA_LUT and CTM */
> +     replaced  = drm_property_replace_blob(&crtc_state->degamma_lut,
> +                                           crtc->has_gamma_prop ? 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,
> +                                           crtc->has_gamma_prop ? blob : 
> NULL);
>       crtc_state->color_mgmt_changed |= replaced;
>  
>       ret = drm_atomic_commit(state);
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c 
> b/drivers/gpu/drm/drm_color_mgmt.c
> index 3bcabc2f6e0e..956e59d5f6a7 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -176,6 +176,8 @@ void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
>                                          degamma_lut_size);
>       }
>  
> +     crtc->has_degamma_prop = !!degamma_lut_size;
> +
>       if (has_ctm)
>               drm_object_attach_property(&crtc->base,
>                                          config->ctm_property, 0);
> @@ -187,6 +189,8 @@ void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
>                                          config->gamma_lut_size_property,
>                                          gamma_lut_size);
>       }
> +
> +     crtc->has_gamma_prop = !!gamma_lut_size;
>  }
>  EXPORT_SYMBOL(drm_crtc_enable_color_mgmt);
>  
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 25edf670867c..b0906ef97617 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -1001,6 +1001,9 @@ static int setcmap_atomic(struct fb_cmap *cmap, struct 
> fb_info *info)
>       drm_client_for_each_modeset(modeset, &fb_helper->client) {
>               crtc = modeset->crtc;
>  
> +             if (!crtc->has_gamma_prop && !crtc->has_degamma_prop)
> +                     continue;
> +
>               if (!gamma_lut)
>                       gamma_lut = setcmap_new_gamma_lut(crtc, cmap);
>               if (IS_ERR(gamma_lut)) {
> @@ -1015,11 +1018,12 @@ static int setcmap_atomic(struct fb_cmap *cmap, 
> struct fb_info *info)
>                       goto out_state;
>               }
>  
> +             /* Set GAMMA/DEGAMMA_LUT and reset DEGAMMA/GAMMA_LUT and CTM */
>               replaced  = drm_property_replace_blob(&crtc_state->degamma_lut,
> -                                                   NULL);
> +                                                   crtc->has_gamma_prop ? 
> NULL : gamma_lut);
>               replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
>               replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
> -                                                   gamma_lut);
> +                                                   crtc->has_gamma_prop ? 
> gamma_lut : NULL);
>               crtc_state->color_mgmt_changed |= replaced;
>       }
>  
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index ba839e5e357d..4d9e217e5040 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -1084,6 +1084,9 @@ struct drm_crtc {
>        */
>       uint16_t *gamma_store;
>  
> +     bool has_gamma_prop : 1;
> +     bool has_degamma_prop : 1;
> +
>       /** @helper_private: mid-layer private data */
>       const struct drm_crtc_helper_funcs *helper_private;
>  

-- 
Regards,

Laurent Pinchart
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