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From:   Chun-Kuang Hu <chunkuang.hu@kernel.org>
Date:   Thu, 10 Dec 2020 23:50:16 +0800
Message-ID: <CAAOTY_-aYFz1Xg6r2ur+BF_k_35F3qNLLb16_2c0MaMsYre-+w@mail.gmail.com>
Subject: Re: [PATCH v8, 5/6] drm/mediatek: add RDMA fifo size error handle
To:     Yongqiang Niu <yongqiang.niu@mediatek.com>
Cc:     CK Hu <ck.hu@mediatek.com>, Philipp Zabel <p.zabel@pengutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        DTML <devicetree@vger.kernel.org>,
        David Airlie <airlied@linux.ie>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
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Hi, Yongqiang:

Yongqiang Niu <yongqiang.niu@mediatek.com> =E6=96=BC 2020=E5=B9=B412=E6=9C=
=8810=E6=97=A5 =E9=80=B1=E5=9B=9B =E4=B8=8B=E5=8D=885:08=E5=AF=AB=E9=81=93=
=EF=BC=9A
>
> This patch add RDMA fifo size error handle
> rdma fifo size will not always bigger than the calculated threshold
> if that case happened, we need set fifo size as the threshold
>
> Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_rdma.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c b/drivers/gpu/drm/m=
ediatek/mtk_disp_rdma.c
> index 794acc5..0508392 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> @@ -151,6 +151,10 @@ static void mtk_rdma_config(struct mtk_ddp_comp *com=
p, unsigned int width,
>          * account for blanking, and with a pixel depth of 4 bytes:
>          */
>         threshold =3D width * height * vrefresh * 4 * 7 / 1000000;
> +
> +       if (threshold > rdma_fifo_size)
> +               threshold =3D rdma_fifo_size;

If the formula is not correct, you should fix the formula not work around.

Regards,
Chun-Kuang.

> +
>         reg =3D RDMA_FIFO_UNDERFLOW_EN |
>               RDMA_FIFO_PSEUDO_SIZE(rdma_fifo_size) |
>               RDMA_OUTPUT_VALID_FIFO_THRESHOLD(threshold);
> --
> 1.8.1.1.dirty
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