Re: [PATCH v2 2/2] hwmon: ltc4282: add support for the LTC4282 chip

[Andy Shevchenko <andy@kernel.org>]

On Thu, Nov 30, 2023 at 11:20:32AM +0100, Nuno Sá wrote:
> On Wed, 2023-11-29 at 21:55 +0100, Linus Walleij wrote:
> > On Wed, Nov 29, 2023 at 5:08 PM Nuno Sá <noname.nuno@gmail.com> wrote:
> > 
> > > Cool, I actually thought that having the direction + get/set stuff would be weird
> > > given the fact that we can only PULL_LOW or HIGH_Z the pins.
> > 
> > There are several drivers in the kernel that implement .set_config(),
> > it's existing and should be enabled if it has uses.
> 
> Yeah, it might make sense to support it specially for the input case. AFAICT, if I
> use the .set_config() (but from a quick look I think we will need to add support for
> it in gpiolib for the high-z configuration), then I can't use the gpio_regmap stuff.
> As the driver stands I don't think I could do it anyways because setting gpio2-3 and
> alert requires to write 0 on the register rather than 1. But again, I'm still very
> suspicious about the whole thing. The datasheet states:
> 
> "GPIO1-GPIO3 and ALERT all have comparators monitoring
> the voltage on these pins with a threshold of 1.28V even when
> the pins are configured as outputs."
> 
> But we can't really set the direction for gpio2-3 and the alert pins (only getting
> the level and setting it as PULL_LOW or HIGH_Z. gpio1 is the only one where we can
> configure it as input or open drain ouput. Bah, I'll try to see if someone internally
> can shed some light on this.

I have better proposal. If these GPIOs are not needed for the main
functionality of the hardware, can we just left it out for now and implement
later if required?

-- 
With Best Regards,
Andy Shevchenko