linux-kernel - Re: [PATCH 3/4] drm/mediatek: fix the wrong pixel clock when resolution is 4K

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Message-ID: <1469429375.11841.69.camel@mtksdaap41>
Date:	Mon, 25 Jul 2016 14:49:35 +0800
From:	CK Hu <ck.hu@...iatek.com>
To:	Bibby Hsieh <bibby.hsieh@...iatek.com>
CC:	David Airlie <airlied@...ux.ie>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	<dri-devel@...ts.freedesktop.org>,
	<linux-mediatek@...ts.infradead.org>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Cawa Cheng <cawa.cheng@...iatek.com>,
	Daniel Kurtz <djkurtz@...omium.org>,
	"Philipp Zabel" <p.zabel@...gutronix.de>,
	YT Shen <yt.shen@...iatek.com>,
	"Thierry Reding" <thierry.reding@...il.com>,
	Mao Huang <littlecvr@...omium.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	"Sascha Hauer" <kernel@...gutronix.de>,
	Junzhi Zhao <junzhi.zhao@...iatek.com>
Subject: Re: [PATCH 3/4] drm/mediatek: fix the wrong pixel clock when
 resolution is 4K

Hi, Bibby:

On Mon, 2016-07-25 at 14:24 +0800, Bibby Hsieh wrote:
> Hi, CK,
> 
> Thanks for your comments.
> 
> On Wed, 2016-07-20 at 15:57 +0800, CK Hu wrote:
> > Hi, Bibby:
> > 
> > Some comments inline.
> > 
> > On Wed, 2016-07-20 at 12:03 +0800, Bibby Hsieh wrote:
> > > From: Junzhi Zhao <junzhi.zhao@...iatek.com>
> > > 
> > > Pixel clock should be 297MHz when resolution is 4K.
> > > 
> > > Signed-off-by: Junzhi Zhao <junzhi.zhao@...iatek.com>
> > > Signed-off-by: Bibby Hsieh <bibby.hsieh@...iatek.com>
> > > ---
> > >  drivers/gpu/drm/mediatek/mtk_dpi.c |  184 +++++++++++++++++++++++++-----------
> > >  1 file changed, 131 insertions(+), 53 deletions(-)
> > > 

[snip...]

> > >  
> > > +static int mt8173_parse_clk_from_dt(struct mtk_dpi *dpi, struct device_node *np)
> > > +{
> > > +	int i;
> > > +
> > > +	for (i = 0; i < ARRAY_SIZE(mtk_dpi_clk_names); i++) {
> > > +		dpi->clk[i] = of_clk_get_by_name(np,
> > > +						  mtk_dpi_clk_names[i]);
> > > +		if (IS_ERR(dpi->clk[i]))
> > > +			return PTR_ERR(dpi->clk[i]);
> > > +	}
> > > +	return 0;
> > > +}
> > 
> > I think parsing device tree is a pure SW behavior. Would this vary for
> > different MTK soc?
> > 
> Yes

I can not imaging that, so could you give me an example source code of
other MTK soc for parse_clk_from_dt()?

> > > +
> > > +
> > > +static const struct mtk_dpi_conf mt8173_conf = {
> > > +	.parse_clk_from_dt = mt8173_parse_clk_from_dt,
> > > +	.clk_config = mt8173_clk_config,
> > > +};
> > > +
> > > +static const struct of_device_id mtk_dpi_of_ids[] = {
> > > +	{ .compatible = "mediatek,mt8173-dpi",
> > > +		.data = &mt8173_conf,
> > > +	},
> > > +	{}
> > > +};
> > > +
> > >  static int mtk_dpi_probe(struct platform_device *pdev)
> > >  {
> > >  	struct device *dev = &pdev->dev;
> > >  	struct mtk_dpi *dpi;
> > >  	struct resource *mem;
> > > +	struct device_node *np = dev->of_node;
> > >  	struct device_node *ep, *bridge_node = NULL;
> > >  	int comp_id;
> > > +	const struct of_device_id *match;
> > > +	struct mtk_dpi_conf *conf;
> > >  	int ret;
> > >  
> > > +	match = of_match_node(mtk_dpi_of_ids, dev->of_node);
> > > +	if (!match)
> > > +		return -ENODEV;
> > > +
> > >  	dpi = devm_kzalloc(dev, sizeof(*dpi), GFP_KERNEL);
> > >  	if (!dpi)
> > >  		return -ENOMEM;
> > >  
> > >  	dpi->dev = dev;
> > > +	dpi->data = (void *)match->data;
> > > +	conf = (struct mtk_dpi_conf *)match->data;
> > >  
> > >  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > >  	dpi->regs = devm_ioremap_resource(dev, mem);
> > > @@ -679,24 +777,9 @@ static int mtk_dpi_probe(struct platform_device *pdev)
> > >  		return ret;
> > >  	}
> > >  
> > > -	dpi->engine_clk = devm_clk_get(dev, "engine");
> > > -	if (IS_ERR(dpi->engine_clk)) {
> > > -		ret = PTR_ERR(dpi->engine_clk);
> > > -		dev_err(dev, "Failed to get engine clock: %d\n", ret);
> > > -		return ret;
> > > -	}
> > > -
> > > -	dpi->pixel_clk = devm_clk_get(dev, "pixel");
> > > -	if (IS_ERR(dpi->pixel_clk)) {
> > > -		ret = PTR_ERR(dpi->pixel_clk);
> > > -		dev_err(dev, "Failed to get pixel clock: %d\n", ret);
> > > -		return ret;
> > > -	}
> > > -
> > > -	dpi->tvd_clk = devm_clk_get(dev, "pll");
> > > -	if (IS_ERR(dpi->tvd_clk)) {
> > > -		ret = PTR_ERR(dpi->tvd_clk);
> > > -		dev_err(dev, "Failed to get tvdpll clock: %d\n", ret);
> > > +	ret = conf->parse_clk_from_dt(dpi, np);
> > > +	if (ret) {
> > > +		dev_err(dev, "parse tvd div clk failed!");
> > >  		return ret;
> > >  	}
> > >  
> > > @@ -754,11 +837,6 @@ static int mtk_dpi_remove(struct platform_device *pdev)
> > >  	return 0;
> > >  }
> > >  
> > > -static const struct of_device_id mtk_dpi_of_ids[] = {
> > > -	{ .compatible = "mediatek,mt8173-dpi", },
> > > -	{}
> > > -};
> > > -
> > >  struct platform_driver mtk_dpi_driver = {
> > >  	.probe = mtk_dpi_probe,
> > >  	.remove = mtk_dpi_remove,
> > 
> > Regards,
> > CK
> > 
> 


Regards,
CK
>