Re: [PATCH v2] pwm-backlight: fix the panel power sequence

From	YH Huang <yh.huang@mediatek.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] pwm-backlight: fix the panel power sequence
Date	2015-11-03 09:20 +0100
Message-ID	<qqEYX-9k-45@gated-at.bofh.it> (permalink)
References	(1 earlier) <qk9Ev-2dv-17@gated-at.bofh.it> <qmpOO-6iz-17@gated-at.bofh.it> <qoXCG-23G-17@gated-at.bofh.it> <qpcBH-30K-7@gated-at.bofh.it> <qpfge-4FN-23@gated-at.bofh.it>
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On Fri, 2015-10-30 at 11:34 +0100, Philipp Zabel wrote:
> Am Freitag, den 30.10.2015, 15:41 +0800 schrieb YH Huang:
> > > That won't work if the gpio is still configured as input. How about I
> > > add the GPIOD_ASIS change to my patch you remove that and the above from
> > > yours?
> > 
> > I revise these two lines 
> > if (pb->enable_gpio)
> > 	gpiod_direction_output(pb->enable_gpio, 0);
> > into
> > if (pb->enable_gpio) {
> > 	if(gpiod_get_value(pb->enable_gpio) == 0)
> > 		gpiod_direction_output(pb->enable_gpio, 0);
> > 	else
> > 		gpiod_direction_output(pb->enable_gpio, 1);
> > }
> 
> If the GPIO is still configured as an input, the return value of
> gpiod_get_value could be random.
> 
> > I am not sure what "phandle" is working for.
> 
> The reasoning is that devices where there is no phandle link pointing to
> the backlight (for example from a simple-panel node), we should keep the
> current default behaviour (enable during probe).

I have a little problem for the current default behaviour.
Should we enable during probe?

Before this patch ( http://patchwork.ozlabs.org/patch/324690/ ),
we disable "enable-gpio" in the probe function.

Do you have any idea of this?

Regards,
YH Huang


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Re: [PATCH v2] pwm-backlight: fix the panel power sequence YH Huang <yh.huang@mediatek.com> - 2015-11-03 09:20 +0100
  Re: [PATCH v2] pwm-backlight: fix the panel power sequence Philipp Zabel <p.zabel@pengutronix.de> - 2015-11-03 12:10 +0100
    Re: [PATCH v2] pwm-backlight: fix the panel power sequence YH Huang <yh.huang@mediatek.com> - 2015-11-04 02:50 +0100
      Re: [PATCH v2] pwm-backlight: fix the panel power sequence Philipp Zabel <p.zabel@pengutronix.de> - 2015-11-05 10:50 +0100
        Re: [PATCH v2] pwm-backlight: fix the panel power sequence YH Huang <yh.huang@mediatek.com> - 2015-11-06 09:40 +0100

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