On Thu, Nov 19, 2015 at 09:39:11AM +0100, Neil Armstrong wrote:
> Hi Andrew,
>
> On 11/19/2015 12:29 AM, Andrew Lunn wrote:
> > + gpio = of_get_named_gpio_flags(child, "reset-gpios", 0,
> > + &flags);
> > + if (gpio_is_valid(gpio)) {
> > + ret = devm_gpio_request_one(dev, gpio, flags,
> > + "switch_reset");
> > + if (ret)
> > + goto out_free_chip;
> > +
> > + cd->reset = gpio;
> > + cd->reset_flags = flags;
> > + off = (flags && OF_GPIO_ACTIVE_LOW ? 1 : 0);
> > + gpio_direction_output(cd->reset, off);
> > + }
> > +
> > for_each_available_child_of_node(child, port) {
> > port_reg = of_get_property(port, "reg", NULL);
> > if (!port_reg)
> >
>
> You could also use :
> gpio = of_get_named_gpio(child, "reset-gpios", 0)
> devm_gpio_request(dev, gpio, "switch_reset")
>
> and :
> cd->reset = gpio_to_desc(gpio);
>
> and cd->switch reset to struct gpio_desc *reset
>
> to use the gpiod calls afterward. The flags are no more needed.
Hi Neil
I really wanted to use gpiod, since as you said, it takes care of
active low/active high. I tried all sorts of combinations. The problem
with this one is that desc->flags is set in gpiod_parse_flags(), which
is only called from gpiod_get_index(), which is limited to gpios in
the root of the devices subtree. I was 'lucky' in that my reset is
active low, so i noticed the problem when my switch failed to probe,
being held in reset, because the ACTIVE_LOW flag in DT is being ignored.
It seems like gpiod is backwards compatible to gpio, but gpio is not
forward compatible to gpiod.
Andrew
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