On 05/12/2014 11:53 PM, FanWu wrote: ... > About the glitch I mentioned before, I want to make myself clear. > If there is a case like the following one: > pinctrl-0 = <&a_grp_settingA>; > pinctrl-1 = <&a_grp_settingB>; > "a_grp_settingA" and "a_grp_settingB" are used to described the same > Pin's different mux and function configuration > In my understanding, > When there is a need to switch Pin group state, the current code will > disable "a_grp_settingA" first ahead of enabling "a_grp_settingB", right ?
Yes. > Do you mean the case I mentioned will not be a glitch ? I guess you're talking about that: >> In the original code, the Pin setting will be changed to the >> disabled/safe state when Pin state is switched if the old setting is not >> existed in new state rather than directly switched to the new Pin >> setting. Also a possible glitch? Yes, in this case, there is no glitch. However, there is certainly a change in HW configuration. A glitch is a temporary short-term accidental change in output value or configuration. In the case quoted immediately above, the change is permanent - at least until some other state is activated later. Hence, there is no glitch. However, there certainly is a change in HW configuration, and that could be just as problematic, depending on the HW and exact pin configuration. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/