linux-kernel - Re: [PATCH] drm/mediatek: Fix config_updating flag never false when no mbox channel

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Message-ID: <5255301c4520a625144debb9daacdd62ce7dd2cd.camel@mediatek.com>
Date: Mon, 24 Feb 2025 05:31:44 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>, "AngeloGioacchino Del
 Regno" <angelogioacchino.delregno@...labora.com>
CC: Singo Chang (張興國) <Singo.Chang@...iatek.com>,
	"treapking@...omium.org" <treapking@...omium.org>,
	Yongqiang Niu (牛永强)
	<yongqiang.niu@...iatek.com>, Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Xavier Chang (張獻文) <Xavier.Chang@...iatek.com>,
	Sirius Wang (王皓昱) <Sirius.Wang@...iatek.com>,
	"wenst@...omium.org" <wenst@...omium.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] drm/mediatek: Fix config_updating flag never false when
 no mbox channel

On Mon, 2025-02-24 at 13:12 +0800, Jason-JH Lin wrote:
> When CONFIG_MTK_CMDQ is enabled, if the display is controlled by the CPU
> while other hardware is controlled by the GCE, the display will encounter
> a mbox request channel failure.
> However, it will still enter the CONFIG_MTK_CMDQ statement, causing the
> config_updating flag to never be set to false. As a result, no page flip
> event is sent back to user space, and the screen does not update.

Reviewed-by: CK Hu <ck.hu@...iatek.com>

> 
> Fixes: da03801ad08f ("drm/mediatek: Move mtk_crtc_finish_page_flip() to ddp_cmdq_cb()")
> Signed-off-by: Jason-JH Lin <jason-jh.lin@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_crtc.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_crtc.c b/drivers/gpu/drm/mediatek/mtk_crtc.c
> index 5674f5707cca..cfc4867296b8 100644
> --- a/drivers/gpu/drm/mediatek/mtk_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_crtc.c
> @@ -620,13 +620,14 @@ static void mtk_crtc_update_config(struct mtk_crtc *mtk_crtc, bool needs_vblank)
>  
>  		mbox_send_message(mtk_crtc->cmdq_client.chan, cmdq_handle);
>  		mbox_client_txdone(mtk_crtc->cmdq_client.chan, 0);
> +		goto update_config_out;
>  	}
> -#else
> +#endif
>  	spin_lock_irqsave(&mtk_crtc->config_lock, flags);
>  	mtk_crtc->config_updating = false;
>  	spin_unlock_irqrestore(&mtk_crtc->config_lock, flags);
> -#endif
>  
> +update_config_out:
>  	mutex_unlock(&mtk_crtc->hw_lock);
>  }
>