[PATCH v3 13/14] drm/mediatek: Support DRM plane alpha in OVL

[Adam Thiede]

On 6/19/24 11:38, Hsiao Chien Sung via B4 Relay wrote:
> From: Hsiao Chien Sung <shawn.sung at mediatek.com>
> 
> Set the plane alpha according to DRM plane property.
> 
> Reviewed-by: CK Hu <ck.hu at mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
> Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")
> Signed-off-by: Hsiao Chien Sung <shawn.sung at mediatek.com>
> ---
>   drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> index 943db4f1bd6b..4b370bc0746d 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> @@ -458,8 +458,10 @@ void mtk_ovl_layer_config(struct device *dev, unsigned int idx,
>   	}
>   
>   	con = ovl_fmt_convert(ovl, fmt);
> -	if (state->base.fb && state->base.fb->format->has_alpha)
> -		con |= OVL_CON_AEN | OVL_CON_ALPHA;
> +	if (state->base.fb) {
> +		con |= OVL_CON_AEN;
> +		con |= state->base.alpha & OVL_CON_ALPHA;
> +	}
>   
>   	/* CONST_BLD must be enabled for XRGB formats although the alpha channel
>   	 * can be ignored, or OVL will still read the value from memory.
> 
Hello, I believe that this commit has caused a problem for my Lenovo 
C330 Chromebook running postmarketOS.

With kernel 6.11 this device didn't show any text on the tty or splash 
screen during booting, but graphical environments (wayland, xorg) do 
appear. With a few bisects I found it to be this commit. With it 
reverted I'm able to get text on the tty again.

The kernel config is here: 
https://gitlab.com/adamthiede/pmaports/-/tree/mt8173-611/device/community/linux-postmarketos-mediatek-mt8173/
To be perfectly clear, this device is not running Chrome OS.

I'm still rather new at this so it's also likely I got something wrong 
or have a bad configuration option. If there is any more information I 
can provide please let me know. Thank you.

- Adam Thiede