linux-kernel - Re: [PATCH v2 2/3] drm/mediatek: Add pm_runtime support for GCE power control

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Message-ID: <1479834ed116744a089e08ff6ce217f06a02ed62.camel@mediatek.com>
Date: Fri, 5 Sep 2025 05:28:42 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: "jassisinghbrar@...il.com" <jassisinghbrar@...il.com>,
	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>, "mchehab@...nel.org"
	<mchehab@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
	"simona@...ll.ch" <simona@...ll.ch>,
	Sirius Wang (王皓昱) <Sirius.Wang@...iatek.com>,
	Zhenxing Qin (秦振兴) <Zhenxing.Qin@...iatek.com>,
	Xiandong Wang (王先冬)
	<Xiandong.Wang@...iatek.com>,
	Yongqiang Niu (牛永强)
	<yongqiang.niu@...iatek.com>, Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	Paul-pl Chen (陳柏霖) <Paul-pl.Chen@...iatek.com>,
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"fshao@...omium.org" <fshao@...omium.org>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>, Singo Chang (張興國)
	<Singo.Chang@...iatek.com>, "wenst@...omium.org" <wenst@...omium.org>,
	"airlied@...il.com" <airlied@...il.com>,
	Jarried Lin (林裕哲) <Jarried.Lin@...iatek.com>,
	Xavier Chang (張獻文) <Xavier.Chang@...iatek.com>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/3] drm/mediatek: Add pm_runtime support for GCE power
 control

On Fri, 2025-08-29 at 17:15 +0800, Jason-JH Lin wrote:
> Call pm_runtime_resume_and_get() before accessing GCE hardware in
> mbox_send_message(), and invoke pm_runtime_put_autosuspend() in the
> cmdq callback to release the PM reference and start autosuspend for
> GCE. This ensures correct power management for the GCE device.

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

> 
> Fixes: 8afe816b0c99 ("mailbox: mtk-cmdq-mailbox: Implement Runtime PM with autosuspend")
> Signed-off-by: Jason-JH Lin <jason-jh.lin@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_crtc.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_crtc.c b/drivers/gpu/drm/mediatek/mtk_crtc.c
> index bc7527542fdc..c4c6d0249df5 100644
> --- a/drivers/gpu/drm/mediatek/mtk_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_crtc.c
> @@ -283,6 +283,10 @@ static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
>  	unsigned int i;
>  	unsigned long flags;
>  
> +	/* release GCE HW usage and start autosuspend */
> +	pm_runtime_mark_last_busy(cmdq_cl->chan->mbox->dev);
> +	pm_runtime_put_autosuspend(cmdq_cl->chan->mbox->dev);
> +
>  	if (data->sta < 0)
>  		return;
>  
> @@ -618,6 +622,9 @@ static void mtk_crtc_update_config(struct mtk_crtc *mtk_crtc, bool needs_vblank)
>  		mtk_crtc->config_updating = false;
>  		spin_unlock_irqrestore(&mtk_crtc->config_lock, flags);
>  
> +		if (pm_runtime_resume_and_get(mtk_crtc->cmdq_client.chan->mbox->dev) < 0)
> +			goto update_config_out;
> +
>  		mbox_send_message(mtk_crtc->cmdq_client.chan, cmdq_handle);
>  		mbox_client_txdone(mtk_crtc->cmdq_client.chan, 0);
>  		goto update_config_out;