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Message-ID: <315011be-59c6-42b1-be9b-cd2eaf6debd9@collabora.com>
Date:   Tue, 12 Dec 2023 14:27:16 +0100
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v4 11/17] drm/mediatek: Turn off the layers with zero
 width or height
Content-Language: en-US
To:     Hsiao Chien Sung <shawn.sung@mediatek.com>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        CK Hu <ck.hu@mediatek.com>
Cc:     Philipp Zabel <p.zabel@pengutronix.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Chen-Yu Tsai <wenst@chromium.org>, Sean Paul <sean@poorly.run>,
        Fei Shao <fshao@chromium.org>,
        Bibby Hsieh <bibby.hsieh@mediatek.com>,
        dri-devel@lists.freedesktop.org,
        linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
References: <20231212121957.19231-1-shawn.sung@mediatek.com>
 <20231212121957.19231-12-shawn.sung@mediatek.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <20231212121957.19231-12-shawn.sung@mediatek.com>
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Precedence: bulk

Il 12/12/23 13:19, Hsiao Chien Sung ha scritto:
> 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 situations.
> 
> Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>

This commit needs a Fixes tag. Please add the relevant one.

Thanks,
Angelo

> ---
>   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 10d23e76acaa..8789442c039f 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> @@ -156,7 +156,7 @@ 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 73c9e3da56a7..e95331c06815 100644
> --- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
> +++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
> @@ -163,7 +163,12 @@ 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;
>   	}