Re: [PATCH v3] backlight: corgi_lcd: Use gpio_set_value_cansleep() toavoid WARN_ON

From: Jingoo Han
Date: Tue Dec 04 2012 - 20:17:54 EST


On Wednesday, December 05, 2012 7:58 AM, Andrew Morton wrote
> On Tue, 04 Dec 2012 14:28:15 +0900
> Jingoo Han <jg1.han@xxxxxxxxxxx> wrote:
>
> > From: Marko Katic <dromede@xxxxxxxxx>
> >
> > Changing backlight intensity on an Akita (Sharp Zaurus C-1000)
> > triggers WARN_ON message:
>
> Well, I queued it up.
>
> > ...
> >
> > --- a/drivers/video/backlight/corgi_lcd.c
> > +++ b/drivers/video/backlight/corgi_lcd.c
> > @@ -408,11 +408,20 @@ static int corgi_bl_set_intensity(struct corgi_lcd *lcd, int intensity)
> > /* Bit 5 via GPIO_BACKLIGHT_CONT */
> > cont = !!(intensity & 0x20) ^ lcd->gpio_backlight_cont_inverted;
> >
> > - if (gpio_is_valid(lcd->gpio_backlight_cont))
> > - gpio_set_value(lcd->gpio_backlight_cont, cont);
> > + if (gpio_is_valid(lcd->gpio_backlight_cont)) {
> > + if (gpio_cansleep(lcd->gpio_backlight_cont))
> > + gpio_set_value_cansleep(lcd->gpio_backlight_cont, cont);
> > + else
> > + gpio_set_value(lcd->gpio_backlight_cont, cont);
> > + }
>
> But this looks utterly daft. Grant, these two things are the same - do
> we need both of them?

Hi Andrew,

There is another difference, except for warning message.
There is might_sleep_if(extra_checks) in gpio_set_value_cansleep().

Also, I saw the Documentation/gpio.txt as below:

172 /* GPIO OUTPUT */
173 void gpio_set_value(unsigned gpio, int value);
...
213 /* GPIO OUTPUT, might sleep */
214 void gpio_set_value_cansleep(unsigned gpio, int value);


Best regards,
Jingoo Han


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/