linux-kernel - Re: [PATCH v15 07/11] drm/mediatek: Add retry to prevent misjudgment for sink devices

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Date:   Fri, 5 Aug 2022 15:10:59 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        <chunkuang.hu@...nel.org>, <p.zabel@...gutronix.de>,
        <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <mripard@...nel.org>,
        <tzimmermann@...e.de>, <matthias.bgg@...il.com>, <deller@....de>,
        <airlied@...ux.ie>
CC:     <msp@...libre.com>, <granquet@...libre.com>,
        <jitao.shi@...iatek.com>, <wenst@...omium.org>,
        <ck.hu@...iatek.com>, <liangxu.xu@...iatek.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-fbdev@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v15 07/11] drm/mediatek: Add retry to prevent
 misjudgment for sink devices

Hello all,

I will drop this modification becaus after we testing current drivers,
the issue described in commit message does not occur.

BRs,
Bo-Chen

On Thu, 2022-07-28 at 17:40 +0800, Rex-BC Chen wrote:
> On Wed, 2022-07-27 at 11:40 +0200, AngeloGioacchino Del Regno wrote:
> > Il 27/07/22 06:50, Bo-Chen Chen ha scritto:
> > > For some DP dungles, we need to train more than onece to confirm
> > > that we
> > > don't misjudge the status of sink device.
> > 
> > Please fix the typos in your commit title and description.
> > title: misjudgment -> misjudgement
> > desc: dungles->dongles; onece->once
> > 
> > > 
> > > Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> > > ---
> > >   drivers/gpu/drm/mediatek/mtk_dp.c | 21 ++++++++++++++++++---
> > >   1 file changed, 18 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c
> > > b/drivers/gpu/drm/mediatek/mtk_dp.c
> > > index ce817cb59445..80d7d6488105 100644
> > > --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> > > +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> > > @@ -42,6 +42,7 @@
> > >   #define MTK_DP_CHECK_SINK_CAP_TIMEOUT_COUNT 3
> > >   #define MTK_DP_TBC_BUF_READ_START_ADDR 0x08
> > >   #define MTK_DP_TRAIN_DOWNSCALE_RETRY 8
> > > +#define MTK_DP_TRAIN_CLEAR_RETRY 50
> > >   
> > >   struct mtk_dp_train_info {
> > >   	bool tps3;
> > > @@ -1431,11 +1432,25 @@ static int mtk_dp_video_config(struct
> > > mtk_dp *mtk_dp)
> > >   
> > >   static int mtk_dp_training(struct mtk_dp *mtk_dp)
> > >   {
> > > +	short max_retry = MTK_DP_TRAIN_CLEAR_RETRY;
> > >   	int ret;
> > >   
> > > -	ret = mtk_dp_train_start(mtk_dp);
> > > -	if (ret)
> > > -		return ret;
> > > +	/*
> > > +	 * We do retry to confirm that we don't misjudge the sink
> > > status.
> > > +	 * If it is still failed, we can confirm there are some issues
> > > for the
> > > +	 * sink device.
> > > +	 */
> > > +	do {
> > > +		ret = mtk_dp_train_start(mtk_dp);
> > > +		if (!ret)
> > > +			break;
> > > +	} while (--max_retry);
> > > +
> > > +	dev_info(mtk_dp->dev, "dp training clear retry times: %d\n",
> > > +		 MTK_DP_TRAIN_CLEAR_RETRY - max_retry);
> > 
> > dev_dbg() here.
> > 
> > ...after which,
> > 
> > Reviewed-by: AngeloGioacchino Del Regno <
> > angelogioacchino.delregno@...labora.com>
> > 
> 
> Hello Angelo,
> 
> Thanks for your review.
> I will modify these in next version.
> 
> BRs,
> Bo-Chen
> 
> > > +
> > > +	if (!max_retry)
> > > +		return -ETIMEDOUT;
> > >   
> > >   	ret = mtk_dp_video_config(mtk_dp);
> > >   	if (ret)
> > 
> > 
> 
>