linux-kernel - Re: [PATCH v4 1/5] pwm-backlight: enable/disable the PWM before/after LCD enable toggle.

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Date:   Tue, 25 Jul 2017 13:49:27 -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 1/5] pwm-backlight: enable/disable the PWM before/after LCD enable toggle.

On Monday, July 24, 2017 11:14 AM, Daniel Thompson wrote:
> On 21/07/17 11:48, Enric Balletbo i Serra wrote:
> > Before this patch the enable signal was set before the PWM signal and
> > vice-versa on power off. This sequence is wrong, at least, it is on
> > the different panels datasheets that I checked, so I inverted the
> sequence
> > to follow the specs.
> >
> > For reference the following panels have the mentioned sequence:
> >    - N133HSE-EA1 (Innolux)
> >    - N116BGE (Innolux)
> >    - N156BGE-L21 (Innolux)
> >    - B101EAN0 (Auo)
> >    - B101AW03 (Auo)
> >    - LTN101NT05 (Samsung)
> >    - CLAA101WA01A (Chunghwa)
> >
> > 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:
> >   - List the part numbers for the panel checked (Daniel Thompson)
> > Changes since v2:
> >   - Add this as a separate patch (Thierry Reding)
> > Changes since v1:
> >   - None
> >
> >   drivers/video/backlight/pwm_bl.c | 9 +++++----
> >   1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/video/backlight/pwm_bl.c
> b/drivers/video/backlight/pwm_bl.c
> > index 002f1ce..909a686 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_cansleep(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_cansleep(pb->enable_gpio, 0);
> >
> > +	pwm_config(pb->pwm, 0, pb->period);
> > +	pwm_disable(pb->pwm);
> > +
> >   	regulator_disable(pb->power_supply);
> >   	pb->enabled = false;
> >   }
> >