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

From: YH Huang
Date: Fri Oct 30 2015 - 03:42:51 EST

Hi Hpilipp,

On Thu, 2015-10-29 at 16:40 +0100, Philipp Zabel wrote:
> Hi YH,
> Am Donnerstag, den 22.10.2015, 23:12 +0800 schrieb YH Huang:
> > In the case of the panel disabled by the bootloader,
> > your patch still has the following code and always enables the backlight
> > in the probe function.
> > pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
> You are right.
> > What do you think if I remove these two lines in my patch?
> > if (pb->enable_gpio)
> > gpiod_direction_output(pb->enable_gpio, 0);
> 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);
if (pb->enable_gpio) {
if(gpiod_get_value(pb->enable_gpio) == 0)
gpiod_direction_output(pb->enable_gpio, 0);
gpiod_direction_output(pb->enable_gpio, 1);

I am not sure what "phandle" is working for.
My change is like your patch but remove the "phandle related" and
"gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_OUT".
Do we really need these?

Also, do you think it is right that I do the "pwm_enable(pb->pwm);"
before "gpiod_set_value(pb->enable_gpio, 1);" in power on function?

YH Huang

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