On 26.11.2014 21:20, Mark Brown wrote: > On Wed, Nov 26, 2014 at 09:13:50PM +0200, Vladimir Zapolskiy wrote: > >> If I want to enable a fixed regulator (not controlled by >> bootloader/firmware) by Linux on boot or when fixed.ko module is bound, >> shall I specify the same "regulator-boot-on" property? At least this is >> the practical way to enable a fixed and/or gpio regulator right now, but >> is it correct? > > It depends what you're trying to accomplish by doing this. If "regulator-boot-on" is specified and the regulator is enabled by bootloader/firmware, then the kernel re-enables it. If "regulator-boot-on" is specified and the regulator is untouched by bootloader/firmware, then the kernel simply enables it. As far as I understand the latter side-effect is exploited on quite many ARM boards, when there is no defined regulator consumer, but I agree that it looks hackish. My assumption is that probably fixed regulator logic around "regulator-boot-on" property should be changed, so that the kernel will not attempt to physically re-enable/enable the "regulator-boot-on" regulator at all, then misusage of the property should gone forced by necessity of finding a proper regulator consumer. >> Or should the regulator always be enabled externally (assuming >> "regulator-always-on" is omitted) after registration independently on >> "regulator-boot-on" property? > > Best practice is that there should be a consumer which keeps the > regulator enabled whenever it is required. There should normally be > little use for boot-on, it's mostly there to ease handover from the > bootloader in cases where we can't read the hardware state - if you're > not sure if you should use it the chances are you shouldn't. > Right, thank you for explanation. -- With best wishes, Vladimir -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
