linux-kernel - Re: [PATCH v12 11/14] drm/mediatek: dpi: Add tvd

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Message-ID: <7bffe5226a80474f150ef67e36d2b75ea8e8a9d8.camel@mediatek.com>
Date:   Tue, 21 Jun 2022 11:11:55 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     CK Hu <ck.hu@...iatek.com>, <chunkuang.hu@...nel.org>,
        <p.zabel@...gutronix.de>, <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <matthias.bgg@...il.com>,
        <airlied@...ux.ie>
CC:     <msp@...libre.com>, <granquet@...libre.com>,
        <jitao.shi@...iatek.com>, <wenst@...omium.org>,
        <angelogioacchino.delregno@...labora.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>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v12 11/14] drm/mediatek: dpi: Add tvd_clk enable/disable
 flow

On Tue, 2022-06-21 at 10:55 +0800, CK Hu wrote:
> Hi, Bo-Chen:
> 
> On Mon, 2022-06-20 at 20:10 +0800, Bo-Chen Chen wrote:
> > We should enable/disable tvd_clk when power_on/power_off, so add
> > this
> > patch to do this.
> 
> Without this patch, what would happen?
> It seems this patch is redundant for these SoCs:
> 
> static const struct of_device_id mtk_dpi_of_ids[] = {
> 	{ .compatible = "mediatek,mt2701-dpi",
> 	  .data = &mt2701_conf,
> 	},
> 	{ .compatible = "mediatek,mt8173-dpi",
> 	  .data = &mt8173_conf,
> 	},
> 	{ .compatible = "mediatek,mt8183-dpi",
> 	  .data = &mt8183_conf,
> 	},
> 	{ .compatible = "mediatek,mt8192-dpi",
> 	  .data = &mt8192_conf,
> 	},
> 	{ },
> };
> 
> Regards,
> CK
> 

Hello CK,

IMO, this is a bug fix patch. From the usage of clock, if we want to
use it, we should enable it . Therefore, I think we should add this and
I will add a fix tag for this patch.

BRs,
Bo-Chen
> 
> > 
> > Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_dpi.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > index 2717b1741b7a..f83ecb154457 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > @@ -455,6 +455,7 @@ static void mtk_dpi_power_off(struct mtk_dpi
> > *dpi)
> >  	mtk_dpi_disable(dpi);
> >  	clk_disable_unprepare(dpi->pixel_clk);
> >  	clk_disable_unprepare(dpi->engine_clk);
> > +	clk_disable_unprepare(dpi->tvd_clk);
> >  }
> >  
> >  static int mtk_dpi_power_on(struct mtk_dpi *dpi)
> > @@ -464,10 +465,16 @@ static int mtk_dpi_power_on(struct mtk_dpi
> > *dpi)
> >  	if (++dpi->refcount != 1)
> >  		return 0;
> >  
> > +	ret = clk_prepare_enable(dpi->tvd_clk);
> > +	if (ret) {
> > +		dev_err(dpi->dev, "Failed to enable tvd pll: %d\n",
> > ret);
> > +		goto err_refcount;
> > +	}
> > +
> >  	ret = clk_prepare_enable(dpi->engine_clk);
> >  	if (ret) {
> >  		dev_err(dpi->dev, "Failed to enable engine clock:
> > %d\n", ret);
> > -		goto err_refcount;
> > +		goto err_engine;
> >  	}
> >  
> >  	ret = clk_prepare_enable(dpi->pixel_clk);
> > @@ -484,6 +491,8 @@ static int mtk_dpi_power_on(struct mtk_dpi
> > *dpi)
> >  
> >  err_pixel:
> >  	clk_disable_unprepare(dpi->engine_clk);
> > +err_engine:
> > +	clk_disable_unprepare(dpi->tvd_clk);
> >  err_refcount:
> >  	dpi->refcount--;
> >  	return ret;
> 
>