linux-kernel - Re: [PATCH v4 3/5] pwm-backlight: add support for PWM delays proprieties.

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Date:   Wed, 26 Jul 2017 13:01:53 -0400
From:   "Jingoo Han" <jingoohan1@...il.com>
To:     "'Daniel Thompson'" <daniel.thompson@...aro.org>,
        "'Enric Balletbo i Serra'" <enric.balletbo@...labora.com>,
        "'Thierry Reding'" <thierry.reding@...il.com>,
        "'Lee Jones'" <lee.jones@...aro.org>,
        "'Bartlomiej Zolnierkiewicz'" <b.zolnierkie@...sung.com>,
        "'Rob Herring'" <robh+dt@...nel.org>,
        "'Pavel Machek'" <pavel@....cz>,
        "'Richard Purdie'" <rpurdie@...ys.net>,
        "'Jacek Anaszewski'" <jacek.anaszewski@...il.com>,
        "'Heiko Stuebner'" <heiko@...ech.de>
Cc:     <linux-pwm@...r.kernel.org>, <linux-fbdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <groeck@...omium.org>,
        <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH v4 3/5] pwm-backlight: add support for PWM delays proprieties.

On Monday, July 24, 2017 11:22 AM, Daniel Thompson wrote:
> On 21/07/17 11:48, Enric Balletbo i Serra wrote:
> > Some panels (i.e. N116BGE-L41), in their power sequence specifications,
> > request a delay between set the PWM signal and enable the backlight and
> > between clear the PWM signal and disable the backlight. Add support for
> > the new post-pwm-on-delay-ms and pwm-off-delay-ms proprieties to meet
> > the timings.
> >
> > Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> 
> Acked-by: Daniel Thompson <daniel.thompson@...aro.org>

Acked-by: Jingoo Han <jingoohan1@...il.com>

Best regards,
Jingoo Han

> 
> 
> > ---
> > Changes since v3:
> >   - Use two named members instead of pwm_delay[] (Daniel and Pavel)
> >   - Use msleep instead of usleep_range. (Pavel)
> > Changes since v2:
> >   - Move the pwm/enable sequence to another patch (Thierry Reding)
> > Changes since v1:
> >   - As suggested by Daniel Thompson
> >     - Do not assume power-on delay and power-off delay will be the same
> >   - Move the check of dt property to the parse dt function.
> >
> >   drivers/video/backlight/pwm_bl.c | 19 +++++++++++++++++++
> >   include/linux/pwm_backlight.h    |  2 ++
> >   2 files changed, 21 insertions(+)
> >
> > diff --git a/drivers/video/backlight/pwm_bl.c
> b/drivers/video/backlight/pwm_bl.c
> > index 909a686..6cf6109 100644
> > --- a/drivers/video/backlight/pwm_bl.c
> > +++ b/drivers/video/backlight/pwm_bl.c
> > @@ -10,6 +10,7 @@
> >    * published by the Free Software Foundation.
> >    */
> >
> > +#include <linux/delay.h>
> >   #include <linux/gpio/consumer.h>
> >   #include <linux/gpio.h>
> >   #include <linux/module.h>
> > @@ -35,6 +36,8 @@ struct pwm_bl_data {
> >   	struct gpio_desc	*enable_gpio;
> >   	unsigned int		scale;
> >   	bool			legacy;
> > +	unsigned int		post_pwm_on_delay;
> > +	unsigned int		pwm_off_delay;
> >   	int			(*notify)(struct device *,
> >   					  int brightness);
> >   	void			(*notify_after)(struct device *,
> > @@ -56,6 +59,9 @@ static void pwm_backlight_power_on(struct pwm_bl_data
> *pb, int brightness)
> >
> >   	pwm_enable(pb->pwm);
> >
> > +	if (pb->post_pwm_on_delay)
> > +		msleep(pb->post_pwm_on_delay);
> > +
> >   	if (pb->enable_gpio)
> >   		gpiod_set_value_cansleep(pb->enable_gpio, 1);
> >
> > @@ -70,6 +76,9 @@ static void pwm_backlight_power_off(struct pwm_bl_data
> *pb)
> >   	if (pb->enable_gpio)
> >   		gpiod_set_value_cansleep(pb->enable_gpio, 0);
> >
> > +	if (pb->pwm_off_delay)
> > +		msleep(pb->pwm_off_delay);
> > +
> >   	pwm_config(pb->pwm, 0, pb->period);
> >   	pwm_disable(pb->pwm);
> >
> > @@ -175,6 +184,14 @@ static int pwm_backlight_parse_dt(struct device
> *dev,
> >   		data->max_brightness--;
> >   	}
> >
> > +	/*
> > +	 * These values are optional and set as 0 by default, the out
> values
> > +	 * are modified only if a valid u32 value can be decoded.
> > +	 */
> > +	of_property_read_u32(node, "post-pwm-on-delay-ms",
> > +			     &data->post_pwm_on_delay);
> > +	of_property_read_u32(node, "pwm-off-delay-ms", &data-
> >pwm_off_delay);
> > +
> >   	data->enable_gpio = -EINVAL;
> >   	return 0;
> >   }
> > @@ -273,6 +290,8 @@ static int pwm_backlight_probe(struct
> platform_device *pdev)
> >   	pb->exit = data->exit;
> >   	pb->dev = &pdev->dev;
> >   	pb->enabled = false;
> > +	pb->post_pwm_on_delay = data->post_pwm_on_delay;
> > +	pb->pwm_off_delay = data->pwm_off_delay;
> >
> >   	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
> >   						  GPIOD_ASIS);
> > diff --git a/include/linux/pwm_backlight.h
> b/include/linux/pwm_backlight.h
> > index efdd922..62f59c4 100644
> > --- a/include/linux/pwm_backlight.h
> > +++ b/include/linux/pwm_backlight.h
> > @@ -13,6 +13,8 @@ struct platform_pwm_backlight_data {
> >   	unsigned int lth_brightness;
> >   	unsigned int pwm_period_ns;
> >   	unsigned int *levels;
> > +	unsigned int post_pwm_on_delay;
> > +	unsigned int pwm_off_delay;
> >   	/* TODO remove once all users are switched to gpiod_* API */
> >   	int enable_gpio;
> >   	int (*init)(struct device *dev);
> >