linux-kernel - Re: [PATCH v8, 5/6] drm/mediatek: add RDMA fifo size error handle

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Date:   Fri, 11 Dec 2020 08:45:14 +0800
From:   Yongqiang Niu <yongqiang.niu@...iatek.com>
To:     Chun-Kuang Hu <chunkuang.hu@...nel.org>
CC:     CK Hu <ck.hu@...iatek.com>, Philipp Zabel <p.zabel@...gutronix.de>,
        "Rob Herring" <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        DTML <devicetree@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8, 5/6] drm/mediatek: add RDMA fifo size error handle

On Thu, 2020-12-10 at 23:50 +0800, Chun-Kuang Hu wrote:
> Hi, Yongqiang:
> 
> Yongqiang Niu <yongqiang.niu@...iatek.com> 於 2020年12月10日 週四 下午5:08寫道：
> >
> > 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@...iatek.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/mediatek/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 *comp, unsigned int width,
> >          * account for blanking, and with a pixel depth of 4 bytes:
> >          */
> >         threshold = width * height * vrefresh * 4 * 7 / 1000000;
> > +
> > +       if (threshold > rdma_fifo_size)
> > +               threshold = rdma_fifo_size;
> 
> If the formula is not correct, you should fix the formula not work around.
> 
> Regards,
> Chun-Kuang.

how about this:
threshold = max(width * height * vrefresh * 4 * 7 / 1000000,
rdma_fifo_size);
> 
> > +
> >         reg = RDMA_FIFO_UNDERFLOW_EN |
> >               RDMA_FIFO_PSEUDO_SIZE(rdma_fifo_size) |
> >               RDMA_OUTPUT_VALID_FIFO_THRESHOLD(threshold);
> > --
> > 1.8.1.1.dirty
> > _______________________________________________
> > Linux-mediatek mailing list
> > Linux-mediatek@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-mediatek

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