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