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

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Message-ID: <1576223336.9817.3.camel@mtksdaap41>
Date:   Fri, 13 Dec 2019 15:48:56 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Yongqiang Niu <yongqiang.niu@...iatek.com>
CC:     Philipp Zabel <p.zabel@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "David Airlie" <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Mark Rutland <mark.rutland@....com>,
        <dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v2, 1/2] drm/mediatek: Fix gamma correction issue

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@...iatek.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

>  	priv->num_pipes++;
>  	mutex_init(&mtk_crtc->hw_lock);
>