Re: [PATCH v19 10/10] drm/omapdrm: Use of_find_backlight helper

[Sean Paul <seanpaul@chromium.org>]

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@gmail.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.

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