On Fri, Jun 14, 2019 at 10:00:49PM +0530, Manikanta Maddireddy wrote:
[...]
> GPIO based PERST# is per-platform requirement.
> If DT prop is not present, then devm_gpiod_get_from_of_node() returns
> NULL gpio_desc.
>
> struct gpio_desc *gpiod_get_from_of_node(struct device_node *node,
> const char *propname, int index,
> enum gpiod_flags dflags,
> const char *label)
> {
> struct gpio_desc *desc;
> unsigned long lflags = 0;
> enum of_gpio_flags flags;
> bool active_low = false;
> bool single_ended = false;
> bool open_drain = false;
> bool transitory = false;
> int ret;
>
> desc = of_get_named_gpiod_flags(node, propname,
> index, &flags);
>
> if (!desc || IS_ERR(desc)) {
> */* If it is not there, just return NULL */****if (PTR_ERR(desc) == -ENOENT)****return NULL;*
> return desc;
> }
> ...
>
> }
Ok. My point then is that you have no way to enforce this requirement on
platforms that actually need it, I do not even know if there is a
way you can do it (I was thinking along the lines of using a
compatible string to detect whether the GPIO #PERST reset is mandatory)
but maybe this is not even a SOC property.
Maybe what I am asking is overkill, I just wanted to understand.
I was just asking a question to understand how you handle the case
where a GPIO pin definition is missing in DT for a platform that
actually needs it, the driver will probe but nothing will work.
It would be good to describe this and capture it in the commit log.
Thanks,
Lorenzo
