linux-kernel - Re: [PATCH] drm/mediatek: only touch DISP_REG_OVL_PITCH

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Message-ID: <adb6356b-19ea-4350-a691-3487d42c9fe2@collabora.com>
Date: Mon, 16 Dec 2024 12:11:29 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Daniel Golle <daniel@...rotopia.org>,
 Chun-Kuang Hu <chunkuang.hu@...nel.org>,
 Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>,
 Justin Green <greenjustin@...omium.org>,
 Frank Wunderlich <frank-w@...lic-files.de>, John Crispin <john@...ozen.org>,
 dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 stable@...r.kernel.org
Subject: Re: [PATCH] drm/mediatek: only touch DISP_REG_OVL_PITCH_MSB if AFBC
 is supported

Il 15/12/24 23:09, Daniel Golle ha scritto:
> Touching DISP_REG_OVL_PITCH_MSB leads to video overlay on MT2701, MT7623N
> and probably other older SoCs being broken.
> 
> Only touching it on hardware which actually supports AFBC like it was
> before commit c410fa9b07c3 ("drm/mediatek: Add AFBC support to Mediatek
> DRM driver") fixes it.
> 
> Fixes: c410fa9b07c3 ("drm/mediatek: Add AFBC support to Mediatek DRM driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
>   drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> index f731d4fbe8b6..321b40a387cd 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> @@ -545,7 +545,7 @@ void mtk_ovl_layer_config(struct device *dev, unsigned int idx,
>   				      &ovl->cmdq_reg, ovl->regs, DISP_REG_OVL_PITCH_MSB(idx));
>   		mtk_ddp_write_relaxed(cmdq_pkt, hdr_pitch, &ovl->cmdq_reg, ovl->regs,
>   				      DISP_REG_OVL_HDR_PITCH(ovl, idx));
> -	} else {
> +	} else if (ovl->data->supports_afbc) {
>   		mtk_ddp_write_relaxed(cmdq_pkt,
>   				      overlay_pitch.split_pitch.msb,
>   				      &ovl->cmdq_reg, ovl->regs, DISP_REG_OVL_PITCH_MSB(idx));

At this point you should just move the block over a new function....

if (ovl->data->supports_afbc)
	mtk_ovl_afbc_layer_config(ovl, cmdq_pkt, idx, is_afbc);

static void mtk_ovl_afbc_layer_config( .... )
{
	if (is_afbc) {
		.....
	} else {
		.....
	}
}

Cheers,
Angelo