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

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Message-ID: <dc7569baf040a0cf2ba9d176ea69e250dddfabdd.camel@mediatek.com>
Date: Fri, 1 Mar 2024 07:51:11 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: Shawn Sung (宋孝謙) <Shawn.Sung@...iatek.com>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>, "chunkuang.hu@...nel.org"
	<chunkuang.hu@...nel.org>
CC: "linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bibby Hsieh (謝濟遠) <Bibby.Hsieh@...iatek.com>,
	"jason-ch.chen@...iatek.corp-partner.google.com"
	<jason-ch.chen@...iatek.corp-partner.google.com>,
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
	"daniel@...ll.ch" <daniel@...ll.ch>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>, "seanpaul@...omium.org" <seanpaul@...omium.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"airlied@...il.com" <airlied@...il.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, "fshao@...omium.org" <fshao@...omium.org>
Subject: Re: [PATCH v5 06/13] drm/mediatek: Turn off the layers with zero
 width or height

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@...iatek.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.

Regards,
CK

> 
> Fixes: 777b7bc86a0a3 ("drm/mediatek: Add ovl_adaptor support for
> MT8195")
> Fixes: fa97fe71f6f93 ("drm/mediatek: Add ETHDR support for MT8195")
> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 2 +-
>  drivers/gpu/drm/mediatek/mtk_ethdr.c            | 7 ++++++-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> index d4a13a1402148..68a20312ac6f1 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> @@ -157,7 +157,7 @@ void mtk_ovl_adaptor_layer_config(struct device
> *dev, unsigned int idx,
>  	merge = ovl_adaptor->ovl_adaptor_comp[OVL_ADAPTOR_MERGE0 +
> idx];
>  	ethdr = ovl_adaptor->ovl_adaptor_comp[OVL_ADAPTOR_ETHDR0];
>  
> -	if (!pending->enable) {
> +	if (!pending->enable || !pending->width || !pending->height) {
>  		mtk_merge_stop_cmdq(merge, cmdq_pkt);
>  		mtk_mdp_rdma_stop(rdma_l, cmdq_pkt);
>  		mtk_mdp_rdma_stop(rdma_r, cmdq_pkt);
> diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> index 73dc4da3ba3bd..69872b77922eb 100644
> --- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> +++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> @@ -160,7 +160,12 @@ void mtk_ethdr_layer_config(struct device *dev,
> unsigned int idx,
>  	if (idx >= 4)
>  		return;
>  
> -	if (!pending->enable) {
> +	if (!pending->enable || !pending->width || !pending->height) {
> +		/*
> +		 * instead of disabling layer with MIX_SRC_CON directly
> +		 * set the size to 0 to avoid screen shift due to mixer
> +		 * mode switch (hardware behavior)
> +		 */
>  		mtk_ddp_write(cmdq_pkt, 0, &mixer->cmdq_base, mixer-
> >regs, MIX_L_SRC_SIZE(idx));
>  		return;
>  	}