On Mon, Apr 23, 2012 at 3:55 PM, viresh kumar <viresh.linux@xxxxxxxxx> wrote: > On Mon, Apr 23, 2012 at 6:26 PM, Wolfram Sang <w.sang@xxxxxxxxxxxxxx> wrote: >>> + * @set_scl: controller specific scl configuration routine. Only required if >>> + * is_gpio_recovery == false >>> + * @get_sda: controller specific sda read routine. Only required if >>> + * is_gpio_recovery == false and skip_sda_polling == false. >>> + * @get_gpio: called before recover_bus() to get padmux configured for scl line. >>> + * as gpio. Only required if is_gpio_recovery == true. >>> + * @put_gpio: called after recover_bus() to get padmux configured for scl line >>> + * as scl. Only required if is_gpio_recovery == true. >> >> Can't we use the pinmux/pinctrl subsystem here? Not knowing too much >> about it, CCing Linus. > > Can be. But probably true only for architectures where pinctrl is > defined. Linus? We *could* do it by defining a standard state for the pinctrl handle in <linux/pinctrl/pinctrl-state.h> (pending in linux-next) like: #define PINCTRL_STATE_GPIO "gpio" Or so, then have the core grab that using the struct device * of this pin controller, returing it to PINCTRL_STATE_DEFAULT afterwards. It seems a bit scary to do that in core code though, because we don't know which state we should return to, should it really be default state? And what if we're using GPIO bit-banging, then we grab the pins into some state they're already in. So to me it seems better to do this at driver level using these hooks so the driver is in full control of the pinctrl states. Stephen, do you agree? But: Many platforms I've seen actually have the ability to mux their I2C pins into GPIO and bitbang them, sometimes this seems to be used to work around broken silicon for example. And it seems what is done here is simply some instance of bitbanging (am I right?). I wonder if it would make sense to model this in the core, so any I2C driver can specify that it also supports bit-banging using GPIO pins A,B and then this can be used for anything, not just for this recovery. So the above hooks should be possible to use to switch the entire driver over to bitbang mode. 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
