On Thu, Nov 24, 2016 at 10:35 PM, Peter Rosin <peda@xxxxxxxxxx> wrote: > The background is that the gpio- and pinctrl-based i2c-mux drivers > need to know if the device that is used to control the mux of the > i2c-bus is also sitting on that very same i2c-bus. If it is, the > locking has to be different and a bit more relaxed. This relaxed > mode cannot be used always, as that would change the mux behavior > in an unacceptable way for stuff expecting the (traditional) > stricter locking. See Documentation/i2c/i2c-topology for more > details if you need it. > > To check this, the i2c mux drivers dig out the device connected to > each gpio-pin (or pinctrl-state) and walks up the device tree to see > if the root i2c adapter that is muxed is in the loop. > > When I wrote this code, I could not find a clean way to go from a > struct gpio_desc * to the relevant device, short of doing > > #include "../../gpio/gpiolib.h" > > gpio_dev = &gpio_desc->gdev->dev; > > And similarly for pinctrl: > > #include "../../pinctrl/core.h" > > struct pinctrl_setting *setting; > pinctrl_dev = setting->pctldev->dev; > > I'm not very proud of that, and wonder if there is a better way > to get at the needed struct device? If not, then perhaps there > should be? Surely if I can be convinced that we need helpers for this in GPIO and/or pin control we can add them. They just need to be named something reasonable and be generally useful for other situations of similar nature. struct device *gpiod_get_backing_device(struct gpio_desc *d); Is simple but is it really what you want? Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
