linux-kernel - Re: [v2 1/5] drm/mediatek: move mipi_dsi_host

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Date:   Mon, 20 May 2019 15:06:28 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Jitao Shi <jitao.shi@...iatek.com>
CC:     Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
        "Mark Rutland" <mark.rutland@....com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Kumar Gala <galak@...eaurora.org>, <linux-pwm@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        Thierry Reding <treding@...dia.com>,
        "Ajay Kumar" <ajaykumar.rs@...sung.com>,
        Inki Dae <inki.dae@...sung.com>,
        "Rahul Sharma" <rahul.sharma@...sung.com>,
        Sean Paul <seanpaul@...omium.org>,
        Vincent Palatin <vpalatin@...omium.org>,
        Andy Yan <andy.yan@...k-chips.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "Russell King" <rmk+kernel@....linux.org.uk>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>,
        Sascha Hauer <kernel@...gutronix.de>,
        <yingjoe.chen@...iatek.com>, <eddie.huang@...iatek.com>,
        <cawa.cheng@...iatek.com>, <bibby.hsieh@...iatek.com>,
        <stonea168@....com>
Subject: Re: [v2 1/5] drm/mediatek: move mipi_dsi_host_register to probe

On Sun, 2019-05-19 at 17:36 +0800, Jitao Shi wrote:
> On Tue, 2019-05-07 at 17:52 +0800, CK Hu wrote:
> > Hi, Jitao:
> > 
> > On Tue, 2019-04-16 at 14:04 +0800, Jitao Shi wrote:
> > > DSI panel driver need attach function which is inculde in
> > > mipi_dsi_host_ops.
> > > 
> > > If mipi_dsi_host_register is not in probe, dsi panel will
> > > probe fail or more delay.
> > 
> > I think this patch just prevent delay, not to prevent dsi panel probe
> > fail. In [1], you mention mipi_dsi_attach() is called in
> > panel_simple_dsi_probe(), but panel_simple_dsi_probe() is trigger by
> > mipi_dsi_host_register(), so the probe would success.
> > 
> > [1]
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/panel/panel-simple.c?h=v5.0-rc6#n2987
> > 
> > 
> 
> Yes, this just prevent delay.
> 
> > > 
> > > So move the mipi_dsi_host_register to probe from bind.
> > > 
> > > Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> > > ---
> > >  drivers/gpu/drm/mediatek/mtk_dsi.c | 50 ++++++++++++++++++------------
> > >  1 file changed, 30 insertions(+), 20 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > index b00eb2d2e086..6c4ac37f983d 100644
> > > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > @@ -1045,12 +1045,6 @@ static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> > >  		return ret;
> > >  	}
> > >  
> > > -	ret = mipi_dsi_host_register(&dsi->host);
> > > -	if (ret < 0) {
> > > -		dev_err(dev, "failed to register DSI host: %d\n", ret);
> > > -		goto err_ddp_comp_unregister;
> > > -	}
> > > -
> > >  	ret = mtk_dsi_create_conn_enc(drm, dsi);
> > >  	if (ret) {
> > >  		DRM_ERROR("Encoder create failed with %d\n", ret);
> > > @@ -1060,8 +1054,6 @@ static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> > >  	return 0;
> > >  
> > >  err_unregister:
> > > -	mipi_dsi_host_unregister(&dsi->host);
> > > -err_ddp_comp_unregister:
> > >  	mtk_ddp_comp_unregister(drm, &dsi->ddp_comp);
> > >  	return ret;
> > >  }
> > > @@ -1097,31 +1089,37 @@ static int mtk_dsi_probe(struct platform_device *pdev)
> > >  
> > >  	dsi->host.ops = &mtk_dsi_ops;
> > >  	dsi->host.dev = dev;
> > > +	dsi->dev = dev;
> > 
> > Why do this?
> > 
> > Regards,
> > CK
> > 
> 
> There are some error message require this poweron().

So this should not be in this patch. This patch is related to the timing
of mipi_dsi_host_register().

Regards,
CK

> 
> > > +	ret = mipi_dsi_host_register(&dsi->host);
> > > +	if (ret < 0) {
> > > +		dev_err(dev, "failed to register DSI host: %d\n", ret);
> > > +		return ret;
> > > +	}
> > >  
> > >  	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> > >  					  &dsi->panel, &dsi->bridge);
> > >  	if (ret)
> > > -		return ret;
> > > +		goto err_unregister_host;
> > >  
> > >  	dsi->engine_clk = devm_clk_get(dev, "engine");
> > >  	if (IS_ERR(dsi->engine_clk)) {
> > >  		ret = PTR_ERR(dsi->engine_clk);
> > >  		dev_err(dev, "Failed to get engine clock: %d\n", ret);
> > > -		return ret;
> > > +		goto err_unregister_host;
> > >  	}
> > >  
> > >  	dsi->digital_clk = devm_clk_get(dev, "digital");
> > >  	if (IS_ERR(dsi->digital_clk)) {
> > >  		ret = PTR_ERR(dsi->digital_clk);
> > >  		dev_err(dev, "Failed to get digital clock: %d\n", ret);
> > > -		return ret;
> > > +		goto err_unregister_host;
> > >  	}
> > >  
> > >  	dsi->hs_clk = devm_clk_get(dev, "hs");
> > >  	if (IS_ERR(dsi->hs_clk)) {
> > >  		ret = PTR_ERR(dsi->hs_clk);
> > >  		dev_err(dev, "Failed to get hs clock: %d\n", ret);
> > > -		return ret;
> > > +		goto err_unregister_host;
> > >  	}
> > >  
> > >  	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > 
> > 
> > 
> 
>