linux-kernel - Re: [PATCH v2] drm/mediatek: Add wait_event

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Message-ID: <CAAOTY_9SKSwikTwog9aGL1LOdsgbnBFz-7wHRNWxa4fY36_dQg@mail.gmail.com>
Date: Wed, 25 Jun 2025 23:10:22 +0800
From: Chun-Kuang Hu <chunkuang.hu@...nel.org>
To: Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com>
Cc: CK Hu (胡俊光) <ck.hu@...iatek.com>, 
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	"airlied@...il.com" <airlied@...il.com>, Sirius Wang (王皓昱) <Sirius.Wang@...iatek.com>, 
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>, 
	Xiandong Wang (王先冬) <Xiandong.Wang@...iatek.com>, 
	"daniel@...ll.ch" <daniel@...ll.ch>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>, 
	Paul-pl Chen (陳柏霖) <Paul-pl.Chen@...iatek.com>, 
	Zhenxing Qin (秦振兴) <Zhenxing.Qin@...iatek.com>, 
	Project_Global_Chrome_Upstream_Group <Project_Global_Chrome_Upstream_Group@...iatek.com>, 
	Yongqiang Niu (牛永强) <yongqiang.niu@...iatek.com>, 
	"p.zabel@...gutronix.de" <p.zabel@...gutronix.de>, 
	Singo Chang (張興國) <Singo.Chang@...iatek.com>, 
	"wenst@...omium.org" <wenst@...omium.org>, 
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, 
	Jarried Lin (林裕哲) <Jarried.Lin@...iatek.com>, 
	Xavier Chang (張獻文) <Xavier.Chang@...iatek.com>, 
	"matthias.bgg@...il.com" <matthias.bgg@...il.com>
Subject: Re: [PATCH v2] drm/mediatek: Add wait_event_timeout when disabling plane

Hi, Jason:

Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com> 於 2025年6月25日 週三 下午3:40寫道：
>
> On Wed, 2025-06-25 at 06:54 +0000, CK Hu (胡俊光) wrote:
> > On Tue, 2025-06-24 at 19:31 +0800, Jason-JH Lin wrote:
> > > Our hardware registers are set through GCE, not by the CPU.
> > > DRM might assume the hardware is disabled immediately after calling
> > > atomic_disable() of drm_plane, but it is only truly disabled after
> > > the
> > > GCE IRQ is triggered.
> > >
> > > Additionally, the cursor plane in DRM uses async_commit, so DRM
> > > will
> > > not wait for vblank and will free the buffer immediately after
> > > calling
> > > atomic_disable().
> > >
> > > To prevent the framebuffer from being freed before the layer
> > > disable
> > > settings are configured into the hardware, which can cause an IOMMU
> > > fault error, a wait_event_timeout has been added to wait for the
> > > ddp_cmdq_cb() callback,indicating that the GCE IRQ has been
> > > triggered.
> > >
> > > Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC
> > > MT8173.")
> >
> > This patch looks good to me, so
> >
> > Reviewed-by: CK Hu <ck.hu@...iatek.com>
> >
> > But fixes patch is not correct.
> > In "drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.", it does
> > not support cmdq.
> > The first patch to support cmdq is 2f965be7f900 "drm/mediatek: apply
> > CMDQ control flow"
> > I would change fixes tag when I apply this patch.
> >
>
> Thank you very much!
>
> Regards,
> Jason-JH Lin

Applied to mediatek-drm-fixes [1], thanks.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-fixes

Regards,
Chun-Kuang.

>
> > > Signed-off-by: Jason-JH Lin <jason-jh.lin@...iatek.com>
> > > Reviewed-by: AngeloGioacchino Del Regno
> > > <angelogioacchino.delregno@...labora.com>
>