On 07/18/2013 01:25 AM, Tony Lindgren wrote: > * Stephen Warren <swarren@xxxxxxxxxxxxx> [130717 14:21]: >> On 07/16/2013 03:05 AM, Tony Lindgren wrote: >>> To toggle dynamic states, let's add the optional active state in >>> addition to the static default state. Then if the optional active >>> state is defined, we can require that idle and sleep states cover >>> the same pingroups as the active state. >>> >>> Then let's add pinctrl_check_dynamic() and pinctrl_select_dynamic() >>> to use instead of pinctrl_select() to avoid breaking existing users. >>> >>> With pinctrl_check_dynamic() we can check that idle and sleep states >>> match the active state for pingroups during init, and don't need to >>> do it during runtime. >>> >>> Then with the states pre-validated, pinctrl_select_dynamic() can >>> just toggle between the dynamic states without extra checks. >>> >>> Note that pinctr_select_state() still has valid use cases, such as >>> changing states when the pins can be shared between two drivers >>> and don't necessarily cover the same pingroups. For dynamic runtime >>> toggling of pin states, we should eventually always use just >>> pinctrl_select_dynamic(). >>> @@ -1241,7 +1371,13 @@ static int pinctrl_pm_select_state(struct device *dev, struct pinctrl_state *sta >>> return 0; >>> if (IS_ERR(state)) >>> return 0; /* No such state */ >>> - ret = pinctrl_select_state(pins->p, state); >>> + >>> + /* Configured for proper dynamic muxing? */ >>> + if (!IS_ERR(dev->pins->active_state)) >>> + ret = pinctrl_select_dynamic(pins->p, state); >>> + else >>> + ret = pinctrl_select_state(pins->p, state); >> >> Hmmm. I'm not quite sure this is right... Surely this function should >> just do nothing if the dynamic states aren't defined? The system should >> just, and only, be in the "default" state and never do anything else. > > This keeps the existing behaviour. We should be able to drop the > call to pinctrl_select_state() here after the existing use in > drivers has been fixed. How many DT-based systems already have multiple of default/idle/sleep states defined in DT? Right now, since the kernel code uses pinctrl_select_state() to switch between those, the state definitions need to define /all/ pins used by those states, not just the dynamic ones. However, with this series in place, the default state should only include the static pins, and the active/idle/sleep states should only include the dynamic pins. That's a change to the DT bindings, since it changes how the DT must be written, and causes older DTs to be incompatible with newer kernels and vice-versa. So, do we just ignore this DT ABI change again, or insist on doing it in some compatible way? DT ABI-ness is a PITA:-( -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
