Re: [PATCH v2, 1/2] drm/mediatek: Fix gamma correction issue

Yongqiang Niu
2019-12-13T08:03:45Z

On Fri, 2019-12-13 at 15:48 +0800, CK Hu wrote:
> Hi, Yongqiang:
>
> The title is too rough. Any bug of gamma would be this title. I would
> like the title show explicitly what it does.
>
> On Fri, 2019-12-13 at 15:28 +0800, Yongqiang Niu wrote:
> > if there is no gamma function in the crtc
> > display path, don't add gamma property
> > for crtc
> >
> > Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
> > ---
> > drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 10 ++++++++--
> > 1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > index ca4fc47..9a8e1d4 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > @@ -734,6 +734,7 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
> > int pipe = priv->num_pipes;
> > int ret;
> > int i;
> > + uint gamma_lut_size = 0;
> >
> > if (!path)
> > return 0;
> > @@ -785,6 +786,9 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
> > }
> >
> > mtk_crtc->ddp_comp[i] = comp;
> > +
> > + if (comp->funcs->gamma_set)
> > + gamma_lut_size = MTK_LUT_SIZE;
> > }
> >
> > for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)
> > @@ -805,8 +809,10 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
> > NULL, pipe);
> > if (ret < 0)
> > return ret;
> > - drm_mode_crtc_set_gamma_size(&mtk_crtc->base, MTK_LUT_SIZE);
> > - drm_crtc_enable_color_mgmt(&mtk_crtc->base, 0, false, MTK_LUT_SIZE);
> > +
> > + if (gamma_lut_size)
> > + drm_mode_crtc_set_gamma_size(&mtk_crtc->base, gamma_lut_size);
> > + drm_crtc_enable_color_mgmt(&mtk_crtc->base, 0, false, gamma_lut_size);
>
> If there is no gamma, shall we enable color management?
>
> Regards,
> CK

drm_crtc_enable_color_mgmt will check the gamma_lut_size parameter,
if no gamma, gamma_lut_size will be 0, and gamma_lut_size will not attch
gamma property for the crtc
>
> > priv->num_pipes++;
> > mutex_init(&mtk_crtc->hw_lock);
> >