Re: [PATCH v5 06/13] drm/mediatek: Turn off the layers with zero width or height

From: "Shawn Sung (宋孝謙)" <Shawn.Sung@mediatek.com>
To: "CK Hu (胡俊光)" <ck.hu@mediatek.com>,
	"angelogioacchino.delregno@collabora.com"
	<angelogioacchino.delregno@collabora.com>,
	"chunkuang.hu@kernel.org" <chunkuang.hu@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"Bibby Hsieh (謝濟遠)" <Bibby.Hsieh@mediatek.com>,
	"jason-ch.chen@mediatek.corp-partner.google.com"
	<jason-ch.chen@mediatek.corp-partner.google.com>,
	"Nancy Lin (林欣螢)" <Nancy.Lin@mediatek.com>,
	"daniel@ffwll.ch" <daniel@ffwll.ch>,
	"p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
	"seanpaul@chromium.org" <seanpaul@chromium.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"airlied@gmail.com" <airlied@gmail.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"fshao@chromium.org" <fshao@chromium.org>
Subject: Re: [PATCH v5 06/13] drm/mediatek: Turn off the layers with zero width or height
Date: Tue, 19 Mar 2024 07:34:51 +0000	[thread overview]
Message-ID: <7a0774c7851e525b1f245cff747d0034b35edc79.camel@mediatek.com> (raw)
In-Reply-To: <dc7569baf040a0cf2ba9d176ea69e250dddfabdd.camel@mediatek.com>

Hi CK,

On Fri, 2024-03-01 at 07:51 +0000, CK Hu (胡俊光) wrote:
> Hi, Hsiao-chien:
> 
> On Thu, 2024-02-15 at 18:11 +0800, Hsiao Chien Sung wrote:
> > We found that IGT (Intel GPU Tool) will try to commit layers with
> > zero width or height and lead to undefined behaviors in hardware.
> > Disable the layers in such a situation.
> 
> Reviewed-by: CK Hu <ck.hu@mediatek.com>
> 
> I have reviewed ovl driver, ovl does not have this limitation, so
> it's
> better to point out which hardware has this limitation. That's OK if
> you have no information.
> 
Thank you for the confirmation. After checking with the designer, for
MT8195/MT8188, the height setting in OVL can be 0 but width cannot,
otherwise the hardware could hang. Although we are not sure if other
old platforms have the same behavior.

Regards,
Shawn
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