Re: [ANNOUNCE] libgpiod v2.0-rc3 released

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

On Mon, Feb 27, 2023 at 12:36 PM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> On Fri, Feb 24, 2023 at 1:28 PM <andy.shevchenko@xxxxxxxxx> wrote:
>
> > That said, would be nice to have an additional flag (during request?)
> > to tell kernel what it should do with the line after releasing the
> > handle from user space.
>
> I think that kind of lines up with the "default initial values" that have
> been proposed again and again and eventually merged as part
> of the PCF8575 bindings in
> Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
>
> These states are supposed to be set when the driver is initialized.
>
> It would make sense that if a GPIO handle in usespace is released
> and the hardware has lines-initial-states set for its driver, then
> the line should snap back to that state.
>
> +/- however ACPI would define this.

Yeah, but I'm more about lines that are free to use by anybody (read:
user space). When we request the line we can tell the kernel, ok, this
line needs to "keep the state after release", or this line needs to
"reset the state to the previous". The flag should be available only
for user space handles.


-- 
With Best Regards,
Andy Shevchenko