linux-kernel - Re: [PATCH v2] drm/sun4i: Enable output signal premultiplication for DE2/DE3

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Date:   Sun, 05 Jun 2022 22:23:18 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     mripard@...nel.org, wens@...e.org, airlied@...ux.ie,
        daniel@...ll.ch, samuel@...lland.org,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org, megi@....cz,
        Roman Stratiienko <r.stratiienko@...il.com>
Cc:     Roman Stratiienko <r.stratiienko@...il.com>
Subject: Re: [PATCH v2] drm/sun4i: Enable output signal premultiplication for DE2/DE3

Dne nedelja, 05. junij 2022 ob 11:40:18 CEST je Roman Stratiienko napisal(a):
> Otherwise alpha value is discarded, resulting incorrect pixel
> apperance on the display.
> 
> This also fixes missing transparency for the most bottom layer.

Can you explain that a bit more? Also, BSP driver never enables this bit. What 
are we doing differently?

> 
> Test applications and videos w/ w/o this patch are available at [1].
> 
> [1]: https://github.com/GloDroid/glodroid_tests/issues/1

As stated in other emails, commit messages should not contain external links 
(per patch rules).

Best regards,
Jernej

> Signed-off-by: Roman Stratiienko <r.stratiienko@...il.com>
> 
> ---
> Changelog:
> 
> V2: Added code hunk missing in v1
> ---
>  drivers/gpu/drm/sun4i/sun8i_mixer.c | 5 +++--
>  drivers/gpu/drm/sun4i/sun8i_mixer.h | 1 +
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c
> b/drivers/gpu/drm/sun4i/sun8i_mixer.c index 6b1711a9a71f..ba2932aaed08
> 100644
> --- a/drivers/gpu/drm/sun4i/sun8i_mixer.c
> +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c
> @@ -320,8 +320,9 @@ static void sun8i_mixer_mode_set(struct sunxi_engine
> *engine, else
>  		val = 0;
> 
> -	regmap_update_bits(engine->regs, 
SUN8I_MIXER_BLEND_OUTCTL(bld_base),
> -			   SUN8I_MIXER_BLEND_OUTCTL_INTERLACED, 
val);
> +	val |= SUN8I_MIXER_BLEND_OUTCTL_PREMULTIPLY;
> +
> +	regmap_write(engine->regs, SUN8I_MIXER_BLEND_OUTCTL(bld_base), 
val);
> 
>  	DRM_DEBUG_DRIVER("Switching display mixer interlaced mode %s\n",
>  			 interlaced ? "on" : "off");
> diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.h
> b/drivers/gpu/drm/sun4i/sun8i_mixer.h index ebfc276b2464..bc12c95af6f3
> 100644
> --- a/drivers/gpu/drm/sun4i/sun8i_mixer.h
> +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.h
> @@ -65,6 +65,7 @@
>  #define SUN8I_MIXER_BLEND_ROUTE_PIPE_MSK(n)	(0xf << ((n) << 2))
>  #define SUN8I_MIXER_BLEND_ROUTE_PIPE_SHIFT(n)	((n) << 2)
> 
> +#define SUN8I_MIXER_BLEND_OUTCTL_PREMULTIPLY	BIT(0)
>  #define SUN8I_MIXER_BLEND_OUTCTL_INTERLACED	BIT(1)
> 
>  #define SUN50I_MIXER_BLEND_CSC_CTL_EN(ch)	BIT(ch)