linux-kernel - Re: [PATCH] pwm-backlight: fix the panel power sequence

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Message-ID: <1444816875.31675.2.camel@mtksdaap41>
Date:	Wed, 14 Oct 2015 18:01:15 +0800
From:	YH Huang <yh.huang@...iatek.com>
To:	Thierry Reding <thierry.reding@...il.com>
CC:	Jingoo Han <jingoohan1@...il.com>,
	Lee Jones <lee.jones@...aro.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	<linux-pwm@...r.kernel.org>, <linux-fbdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	<yingjoe.chen@...iatek.com>, <yh.huang@...iatek.com>
Subject: Re: [PATCH] pwm-backlight: fix the panel power sequence

Hi all,

If you have any suggestion, please let me know.
Thanks.

Regards,
YH Huang

On Wed, 2015-09-16 at 22:42 +0800, YH Huang wrote:
> In order to match the panel power sequence, disable the enable_gpio
> in the probe function. Also, reorder the code in the power_on and
> power_off function to match the timing.
> 
> Signed-off-by: YH Huang <yh.huang@...iatek.com>
> ---
>  drivers/video/backlight/pwm_bl.c |   15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index eff379b..99eca1e 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -54,10 +54,11 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
>  	if (err < 0)
>  		dev_err(pb->dev, "failed to enable power supply\n");
>  
> +	pwm_enable(pb->pwm);
> +
>  	if (pb->enable_gpio)
>  		gpiod_set_value(pb->enable_gpio, 1);
>  
> -	pwm_enable(pb->pwm);
>  	pb->enabled = true;
>  }
>  
> @@ -66,12 +67,12 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
>  	if (!pb->enabled)
>  		return;
>  
> -	pwm_config(pb->pwm, 0, pb->period);
> -	pwm_disable(pb->pwm);
> -
>  	if (pb->enable_gpio)
>  		gpiod_set_value(pb->enable_gpio, 0);
>  
> +	pwm_config(pb->pwm, 0, pb->period);
> +	pwm_disable(pb->pwm);
> +
>  	regulator_disable(pb->power_supply);
>  	pb->enabled = false;
>  }
> @@ -241,8 +242,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
>  	pb->dev = &pdev->dev;
>  	pb->enabled = false;
>  
> -	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
> -						  GPIOD_OUT_HIGH);
> +	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable");
>  	if (IS_ERR(pb->enable_gpio)) {
>  		ret = PTR_ERR(pb->enable_gpio);
>  		goto err_alloc;
> @@ -264,6 +264,9 @@ static int pwm_backlight_probe(struct platform_device *pdev)
>  		pb->enable_gpio = gpio_to_desc(data->enable_gpio);
>  	}
>  
> +	if (pb->enable_gpio)
> +		gpiod_direction_output(pb->enable_gpio, 0);
> +
>  	pb->power_supply = devm_regulator_get(&pdev->dev, "power");
>  	if (IS_ERR(pb->power_supply)) {
>  		ret = PTR_ERR(pb->power_supply);


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