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

YH Huang
2015-11-03T08:11:39Z

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