On Thu, Oct 29, 2020 at 07:58:39PM +0100, Ricardo Ribalda wrote: > On Thu, Oct 29, 2020 at 7:13 PM Andy Shevchenko > <andy.shevchenko@xxxxxxxxx> wrote: > > On Thu, Oct 29, 2020 at 8:10 PM Ricardo Ribalda <ribalda@xxxxxxxxxx> wrote: > > > On Thu, Oct 29, 2020 at 6:32 PM Ricardo Ribalda <ribalda@xxxxxxxxxx> wrote: > > > > On Thu, Oct 29, 2020 at 6:26 PM Andy Shevchenko > > > > <andy.shevchenko@xxxxxxxxx> wrote: > > > > > On Thu, Oct 29, 2020 at 7:20 PM Andy Shevchenko > > > > > <andy.shevchenko@xxxxxxxxx> wrote: > > > > > > On Thu, Oct 29, 2020 at 7:17 PM Andy Shevchenko > > > > > > <andy.shevchenko@xxxxxxxxx> wrote: ... > > > > > > > > Let me try to explain myself again: > > > > > > > > > > > > > > > > I have a gpio pin that produces IRQs on both edges. so ActiveLevel is Both > > > > > > > > > > > > > > > > The problem is that the value of that pin is inverted: Low means 1 and > > > > > > > > high means 0. > > > > > > > > > > > > > > > > How can I describe that the pin "is inverted" without using the _DSD field? > > > > > > > > > > > > > > "Both edges" and "inverted" or "polarity low" in one sentence make no sense. > > > > > > > > > > > > To be on the constructive side, I can *imagine* so badly designed > > > > > > hardware that uses level and edge at the same time, but before I go to > > > > > > conclusions, can you share relevant (pieces of) datasheet? > > > > > > > > > > The [1] is a real example of how GPIO is being used to detect changing > > > > > of current level of the signal. > > > > > Note, ACPI tables for that device have problems [2], but I guess you > > > > > may get the idea. > > > > > > > > > > > > This is exactly what I need to do. Get an IRQ whenever the value > > > > changes. But the pin is "inverted" > > > > > > > > This is the "schematic" : https://ibb.co/f8GMBbP . I want to pass to > > > > userspace a "1" when the switch is closed and "0" when it is open. > > > > > > > And there are also other devices where the swith works the other way > > > around, so the acpi should be verbose enough to describe both > > > situations. > > > > > > With my proposal (use the same active_low field as with GpioIO) we > > > cover both usecases. > > > > Even without your proposal it's feasible. > > You see, the problem here is that if you describe GPIO as Interrupt, > > the edge and level together make complete nonsense. > > > > Solution: do *not* describe it as Interrupt. > > Now I get my mistake: > > I thought that gpiod_to_irq will not work unless it was a GpioInt() > but it works fine. So in this case I will just convert it to that. It's actually that gpio_to_irq() is solely for GPIOs which initially are not IRQs. > Could we say that doing gpiod_get_value() from a GpioInt() is always > wrong? But it's not wrong. Some cases simply make little or no sense, but in principal why not? Yes, it may be fragile or too much customized. > Can we modify the code to avoid it? GpioInt() is orthogonal to GPIO APIs in Linux kernel. It close to be impossible. Also see above. > Sorry for the confusion and thanks for your help. No problem, you're welcome, it's good that you started a discussion! > > > > > [1]: https://elixir.bootlin.com/linux/latest/source/drivers/extcon/extcon-intel-int3496.c#L138 > > > > > [2]: https://elixir.bootlin.com/linux/latest/source/drivers/extcon/extcon-intel-int3496.c#L45 -- With Best Regards, Andy Shevchenko
