linux-kernel - Re: [PATCH v18 10/10] drm/omapdrm: Use of_find

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Date:   Tue, 23 Jan 2018 22:25:01 +0530
From:   Meghana Madhyastha <meghana.madhyastha@...il.com>
To:     Noralf Trønnes <noralf@...nnes.org>,
        Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        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 v18 10/10] drm/omapdrm: Use of_find_backlight helper

On Tue, Jan 23, 2018 at 03:37:38PM +0100, Noralf Trønnes wrote:
> 
> Den 22.01.2018 15.56, skrev Meghana Madhyastha:
> >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 v18:
> >-Fixed warnings resulting from passing device_node* to of_find_backlight.
> >  Fixed it by passing struct device* to of_find_backlight
> >
> >  drivers/gpu/drm/omapdrm/displays/panel-dpi.c | 33 ++++++++++------------------
> >  1 file changed, 11 insertions(+), 22 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
> >index ac9596251..93b7a176d 100644
> >--- a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
> >+++ b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
> >@@ -156,14 +156,14 @@ static struct omap_dss_driver panel_dpi_ops = {
> >  static int panel_dpi_probe_of(struct platform_device *pdev)
> >  {
> >  	struct panel_drv_data *ddata = platform_get_drvdata(pdev);
> >+	struct device *dev = &pdev->dev;
> >  	struct device_node *node = pdev->dev.of_node;
> >-	struct device_node *bl_node;
> >  	struct omap_dss_device *in;
> >  	int r;
> >  	struct display_timing timing;
> >  	struct gpio_desc *gpio;
> >-	gpio = devm_gpiod_get_optional(&pdev->dev, "enable", GPIOD_OUT_LOW);
> >+	gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_LOW);
> 
> Please don't make unrelated changes like this. It clutters the patch.
> You can just as well use &pdev->dev when getting the backlight also.

I had made the change in order to be more consistent with how the other
drivers were doing this. Most of them had a variable struct device *dev.
However, I can undo this if necessary.

> >  	if (IS_ERR(gpio))
> >  		return PTR_ERR(gpio);
> >@@ -175,47 +175,36 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
> >  	 * timing and order relative to the enable gpio. So for now it's just
> >  	 * ensured that the reset line isn't active.
> >  	 */
> >-	gpio = devm_gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
> >+	gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
> >  	if (IS_ERR(gpio))
> >  		return PTR_ERR(gpio);
> >-	ddata->vcc_supply = devm_regulator_get(&pdev->dev, "vcc");
> >+	ddata->vcc_supply = devm_regulator_get(dev, "vcc");
> >  	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 = of_find_backlight(dev);
> 
> Any reason you don't use the devm_ version here?
> You do remove error_free_backlight...
> 
> With the devm_ version remember to drop the put_device in
> panel_dpi_remove().
> 
> Noralf.
> 
> >-		if (!ddata->backlight)
> >-			return -EPROBE_DEFER;
> >-	}
> >+	if (IS_ERR(ddata->backlight))
> >+		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;
> >+		dev_err(dev, "failed to get video timing\n");
> >+		return r;
> >  	}
> >  	videomode_from_timing(&timing, &ddata->vm);
> >  	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;
> >+		dev_err(dev, "failed to find video source\n");
> >+		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)
>