On Fri, 23 Jul 2021, at 17:45, Andy Shevchenko wrote: > > > On Friday, July 23, 2021, Andrew Jeffery <andrew@xxxxxxxx> wrote: > > Hello, > > > > This series does a bunch of crimes, so it's an RFC. I'm cross-posting to the > > pinctrl/GPIO and LEDs lists because the PCA955x devices impact all of them. What > > needs fixing is the leds-pca955x driver's failure to map the GPIO numberspace to > > the pin numberspace of the PCA955x devices. The series solves that by > > implementing pinctrl and pinmux in the leds-pca955x driver. > > > > Things I'm unsure about: > > > > 1. Patch 1: The pinctrl_gpio_as_pin() API feels a bit dirty, not sure what > > others thoughts are on that (Linus?). > > > > 2. Patch 2: I've added a new callback to hook the entirety of the pinctrl map > > parsing rather than supplying a subnode-specific callback. This was necessary > > to handle the PCA955x devicetree binding in a backwards compatible way. > > > > 3. Patch 4: The PCA955x devices don't actually have any pinmux hardware, but the > > properties of the pinctrl/pinmux subsystems in the kernel map nicely onto the > > problem we have. But it's quite a bit of code... > > > > 4. Patch 6: I also lost a bunch of time to overlooking the get_group_pins() > > callback for pinctrl, and it seems odd to me that it isn't required. > > > > Please review! > > > Sounds like a hack. Yes, possibly. Feedback like this is why I sent the series as an RFC. > I was briefly looking into patches 1-4 and suddenly > realized that the fix can be similar as in PCA9685 (PWM), I.e. we > always have chips for the entire pin space and one may map them > accordingly, requested in one realm (LED) in the other (GPIO) > automatically is BUSY. Or I missed the point? No, you haven't missed the point. I will look at the PCA9685 driver. That said, my goal was to implement the behaviour intended by the existing binding (i.e. fix a bug). However, userspace would never have got the results it expected with the existing driver implementation, so I guess you could argue that no such (useful) userspace exists. Given that, we could adopt the strategy of always defining a gpiochip covering the whole pin space, and parts of the devicetree binding just become redundant. Andrew
