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

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Message-ID: <4a873de158868368818c00fbfee1a03f620ad8c9.camel@mediatek.com>
Date:   Tue, 21 Jun 2022 11:50:54 +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 11:45 +0800, CK Hu wrote:
> On Tue, 2022-06-21 at 11:11 +0800, Rex-BC Chen wrote:
> > 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.
> 
> I think mt8173 chromebook use this driver for HDMI output. So mt8173
> chromebook HDMI could not work normally?
> 
> Regards,
> CK
> 

Hmm..
I am not sure about this. But without this patch, dpi is also working
in mt8183/mt8192. It may be related to the ccf driver. But anyway, I
think we should do this whether ccf driver helps us to enable this
clock.

BRs,
Bo-Chen

> > 
> > 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;
> > > 
> > > 
> > 
> > 
> 
>