linux-kernel - Re: [PATCH v3 2/2] backlight: lm3630a: add an enable gpio for the HWEN pin

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Date:   Thu, 12 Sep 2019 06:40:24 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Andreas Kemnade <andreas@...nade.info>, <lee.jones@...aro.org>,
        <daniel.thompson@...aro.org>, <jingoohan1@...il.com>,
        <jacek.anaszewski@...il.com>, <pavel@....cz>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <b.zolnierkie@...sung.com>,
        <dri-devel@...ts.freedesktop.org>, <linux-leds@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-fbdev@...r.kernel.org>,
        "H. Nikolaus Schaller" <hns@...delico.com>
Subject: Re: [PATCH v3 2/2] backlight: lm3630a: add an enable gpio for the
 HWEN pin

Andreas

On 9/11/19 12:21 PM, Andreas Kemnade wrote:
> For now just enable it in the probe function to allow i2c
> access. Disabling also means resetting the register values
> to default and according to the datasheet does not give
> power savings.
>
> Tested on Kobo Clara HD.
>
> Signed-off-by: Andreas Kemnade <andreas@...nade.info>
> ---
> changes in v2:
> - simplification
> - correct gpio direction initialisation
>
> changes in v3:
> - removed legacy include
>
>   drivers/video/backlight/lm3630a_bl.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
> index 8f84f3684f04..d9e67b9b2571 100644
> --- a/drivers/video/backlight/lm3630a_bl.c
> +++ b/drivers/video/backlight/lm3630a_bl.c
> @@ -12,6 +12,7 @@
>   #include <linux/uaccess.h>
>   #include <linux/interrupt.h>
>   #include <linux/regmap.h>
> +#include <linux/gpio/consumer.h>
>   #include <linux/pwm.h>
>   #include <linux/platform_data/lm3630a_bl.h>
>   
> @@ -48,6 +49,7 @@ struct lm3630a_chip {
>   	struct lm3630a_platform_data *pdata;
>   	struct backlight_device *bleda;
>   	struct backlight_device *bledb;
> +	struct gpio_desc *enable_gpio;
>   	struct regmap *regmap;
>   	struct pwm_device *pwmd;
>   };
> @@ -535,6 +537,13 @@ static int lm3630a_probe(struct i2c_client *client,
>   	}
>   	pchip->pdata = pdata;
>   
> +	pchip->enable_gpio = devm_gpiod_get_optional(&client->dev, "enable",
> +						GPIOD_OUT_HIGH);
> +	if (IS_ERR(pchip->enable_gpio)) {
> +		rval = PTR_ERR(pchip->enable_gpio);
> +		return rval;
> +	}
> +
>   	/* chip initialize */
>   	rval = lm3630a_chip_init(pchip);
>   	if (rval < 0) {

Thanks for the explanation

It looks good to me

Reviewed-by: Dan Murphy <dmurphy@...com>