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Subject: Re: [PATCH v18 10/10] drm/omapdrm: Use of_find_backlight helper
From:   =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= <noralf@tronnes.org>
To:     Meghana Madhyastha <meghana.madhyastha@gmail.com>,
        Lee Jones <lee.jones@linaro.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Sean Paul <seanpaul@chromium.org>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <cover.1516632387.git.meghana.madhyastha@gmail.com>
 <69379bffdebdddf49952eabeaaee7f1dd7cff99c.1516632388.git.meghana.madhyastha@gmail.com>
 <394a73f6-3459-449f-6d9f-4cb52a1d3328@tronnes.org>
 <20180123165501.GA5908@meghana-HP-Pavilion-Notebook>
 <853882e3-5f96-56c9-4fe5-a55fe6fbb030@tronnes.org>
Message-ID: <bcda860f-f538-36b3-f62a-dc93329ea8f3@tronnes.org>
Date:   Tue, 23 Jan 2018 18:43:55 +0100
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Den 23.01.2018 18.41, skrev Noralf Trønnes:
>
> Den 23.01.2018 17.55, skrev Meghana Madhyastha:
>> 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@gmail.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.
>
> It's best to be consistent with the coding style in the driver you're
> changing. If you make an extra dev variable or not isn't that important,
> unless the driver maintainer have a strict coding style for their driver.
>
> I try to stay on the safe side, change as little as possible and do thing
> the way it's done in the driver to increase the change of getting the
> patch accepted as-is the first time around.
>
> The important feedback from me is to remove the unrelated changes.
>

and the use of the devm_ version ofc.

> Noralf.
>
>>
>>>>       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)
>
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