On Wed, Jan 31, 2024 at 10:37 AM Bartosz Golaszewski brgl@bgdev.pl wrote:
[Me]
reset -> virtual "gpio" -> many physical gpios[0..n]
This is a different problem: it supports many users enabling the same GPIO (in Krzysztof's patch it's one but could be more if needed) but - unlike the broken NONEXCLUSIVE GPIOs in GPIOLIB - it counts the number of users and doesn't disable the GPIO for as long as there's at least one.
I don't know if the NONEXCLUSIVE stuff is broken, if you mean reference counting isn't working on them, then that is by design because they were invented for regulators and such use cases that do their own reference counting. It's also used for hacks where people need to look up a desc in a second spot, (perhaps we can fix those better).
As I say in commit b0ce7b29bfcd090ddba476f45a75ec0a797b048a "This solution with a special flag is not entirely elegant and should ideally be replaced by something more careful as this makes it possible for several consumers to enable/disable the same GPIO line to the left and right without any consistency."
I think for regulators (which is the vast majority using it) it isn't broken because the regulator reference counting is working.
So if we solve that problem for reset, we probably should put it in drivers/gpio/* somewhere so we can reuse the same solution for regulators and get rid of NONEXCLUSIVE altogether I think?
The NONEXCLUSIVE stuff was prompted by converting regulators to gpio descriptors, so it was for the greater good one can say. Or the lesser evil :( my judgement can be questioned here.
Yours, Linus Walleij