Re: [PATCH v2 3/6] pinctrl: Add a possibility to configure pins from a gpiolib based drivers

Mika Westerberg
2017-01-13T16:37:54Z

On Fri, Jan 13, 2017 at 04:36:42PM +0100, Linus Walleij wrote:
> On Thu, Jan 12, 2017 at 10:22 AM, Mika Westerberg
> <mika.westerberg@linux.intel.com> wrote:
>
> > Hmm, looking at users of .set_debounce() I can see that the debounce
> > time can be quite large. For example some signals which are connected to
> > physical push-buttons may need > 64ms debounce time.
> >
> > However, the current pinconfig value is defined to be unsigned long
> > which on 32-bit architecture is 32-bits. From that the higher 16-bits
> > are used as config leaving the value to be 16-bits. This gives maximum
> > debounce time of 65535us. I don't think it can cover all the uses of
> > .set_debounce(). This could also be problematic when specifying values
> > for pull resistors.
> >
> > One solution is to convert the packed value to be u64 instead, leaving
> > up to 48-bits for the value. Alternatively we could provide a scale
> > field with the packed format.
>
> Hm yeah as long as all in-kernel users survive I don't see why we
> couldn't just make it 64bit. Is it a big deal?

As long as everyone is using those macros and inline functions from
pinconf-generic.h, I think the conversion should be pretty
straightforward.