linux-kernel - Re: [PATCH v19 10/10] drm/omapdrm: Use of_find

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Date:   Wed, 24 Jan 2018 14:26:48 -0500
From:   Sean Paul <seanpaul@...omium.org>
To:     Meghana Madhyastha <meghana.madhyastha@...il.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Noralf Trønnes <noralf@...nnes.org>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Sean Paul <seanpaul@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v19 10/10] drm/omapdrm: Use of_find_backlight helper

On Wed, Jan 24, 2018 at 02:23:46PM -0500, Sean Paul wrote:
> On Wed, Jan 24, 2018 at 04:41:38PM +0000, Meghana Madhyastha wrote:
> > Replace of_find_backlight_by_node and of the code around it
> > with of_find_backlight helper to avoid repetition of code.
> > 
> > Signed-off-by: Meghana Madhyastha <meghana.madhyastha@...il.com>
> > ---
> > Changes in v19:
> > -Changed to devm version of of_find_backlight in omapdrm (patch 10) 
> > -removed assigning pdev->dev to variable dev in omapdrm (patch 10)
> > 
> >  drivers/gpu/drm/omapdrm/displays/panel-dpi.c | 25 +++++--------------------
> >  1 file changed, 5 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
> > index ac9596251..b4a4006a2 100644
> > --- a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
> > +++ b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
> > @@ -157,7 +157,6 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
> >  {
> >  	struct panel_drv_data *ddata = platform_get_drvdata(pdev);
> >  	struct device_node *node = pdev->dev.of_node;
> > -	struct device_node *bl_node;
> >  	struct omap_dss_device *in;
> >  	int r;
> >  	struct display_timing timing;
> > @@ -183,19 +182,15 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
> >  	if (IS_ERR(ddata->vcc_supply))
> >  		return PTR_ERR(ddata->vcc_supply);
> >  
> > -	bl_node = of_parse_phandle(node, "backlight", 0);
> > -	if (bl_node) {
> > -		ddata->backlight = of_find_backlight_by_node(bl_node);
> > -		of_node_put(bl_node);
> > +	ddata->backlight = devm_of_find_backlight(&pdev->dev);
> >  
> > -		if (!ddata->backlight)
> > -			return -EPROBE_DEFER;
> > -	}
> > +	if (IS_ERR(ddata->backlight))
> 
> AFAICT, devm_of_find_backlight can return NULL. As such, you should be checking
> IS_ERR_OR_NULL here instead of just IS_ERR. Looks like you also made this
> same mistake in other patches in the series, so please fix those up as well.
> 

annnd I should spend more time reading the context of the code. Looks like
backlight is optional here, so this is a valid code path. I'm sorry about that.

So,

Reviewed-by: Sean Paul <seanpaul@...omium.org>

I think every other patch has R-b, so if no one objects in the next day or so,
I'll apply this to drm-misc-next

Sean


> Sean
> 
> > +		return PTR_ERR(ddata->backlight);
> >  
> >  	r = of_get_display_timing(node, "panel-timing", &timing);
> >  	if (r) {
> >  		dev_err(&pdev->dev, "failed to get video timing\n");
> > -		goto error_free_backlight;
> > +		return r;
> >  	}
> >  
> >  	videomode_from_timing(&timing, &ddata->vm);
> > @@ -203,19 +198,12 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
> >  	in = omapdss_of_find_source_for_first_ep(node);
> >  	if (IS_ERR(in)) {
> >  		dev_err(&pdev->dev, "failed to find video source\n");
> > -		r = PTR_ERR(in);
> > -		goto error_free_backlight;
> > +		return PTR_ERR(in);
> >  	}
> >  
> >  	ddata->in = in;
> >  
> >  	return 0;
> > -
> > -error_free_backlight:
> > -	if (ddata->backlight)
> > -		put_device(&ddata->backlight->dev);
> > -
> > -	return r;
> >  }
> >  
> >  static int panel_dpi_probe(struct platform_device *pdev)
> > @@ -270,9 +258,6 @@ static int __exit panel_dpi_remove(struct platform_device *pdev)
> >  
> >  	omap_dss_put_device(in);
> >  
> > -	if (ddata->backlight)
> > -		put_device(&ddata->backlight->dev);
> > -
> >  	return 0;
> >  }
> >  
> > -- 
> > 2.11.0
> > 
> 
> -- 
> Sean Paul, Software Engineer, Google / Chromium OS

-- 
Sean Paul, Software Engineer, Google / Chromium OS