[PATCH v9 2/5] drm/mediatek: ovl: Refine ignore_pixel_alpha comment and placement

[CK Hu (胡俊光)]

Hi, Jason:

On Mon, 2024-10-07 at 15:00 +0800, Jason-JH.Lin wrote:
> Refine the comment for ignore_pixel_alpha flag and move it to
> if (state->fb) statement to make it less conditional.

Reviewed-by: CK Hu <ck.hu at mediatek.com>

> 
> Signed-off-by: Jason-JH.Lin <jason-jh.lin at mediatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> index 8453a72f9e59..ddc826c42653 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> @@ -481,16 +481,16 @@ void mtk_ovl_layer_config(struct device *dev, unsigned int idx,
>  		 */
>  		if (blend_mode || state->base.fb->format->has_alpha)
>  			con |= OVL_CON_AEN;
> -	}
>  
> -	/* CONST_BLD must be enabled for XRGB formats although the alpha channel
> -	 * can be ignored, or OVL will still read the value from memory.
> -	 * For RGB888 related formats, whether CONST_BLD is enabled or not won't
> -	 * affect the result. Therefore we use !has_alpha as the condition.
> -	 */
> -	if ((state->base.fb && !state->base.fb->format->has_alpha) ||
> -	    blend_mode == DRM_MODE_BLEND_PIXEL_NONE)
> -		ignore_pixel_alpha = OVL_CONST_BLEND;
> +		/*
> +		 * Although the alpha channel can be ignored, CONST_BLD must be enabled
> +		 * for XRGB format, otherwise OVL will still read the value from memory.
> +		 * For RGB888 related formats, whether CONST_BLD is enabled or not won't
> +		 * affect the result. Therefore we use !has_alpha as the condition.
> +		 */
> +		if (blend_mode == DRM_MODE_BLEND_PIXEL_NONE || !state->base.fb->format->has_alpha)
> +			ignore_pixel_alpha = OVL_CONST_BLEND;
> +	}
>  
>  	if (pending->rotation & DRM_MODE_REFLECT_Y) {
>  		con |= OVL_CON_VIRT_FLIP;