On Friday, July 29, 2011, Pavel Machek wrote: > Hi! > > > > > Actually, it just occurred to me that if we're waiting for a system > > > > timer and can hand that off to a suitable timer in the PMIC then we can > > > > do a suspend to RAM for the deep idle state from the hardware point of > > > > view. > > > > > > Yep. At LinuxCon Cambridge two years ago, we had a discussion about > > > whether it would be possible to enter ACPI S-states from CPUIdle (or some > > > idle governor) on Intel chips. If I remember correctly, the conclusion > > > was that ACPI always disables the screen/backlight, so it would only be > > > useful for situations where that was acceptable. > > Well, auto suspending when screensaver is active would still be > useful. > > (And IIRC some machines kept screen on when in S-state unless driver > powered it down... but that might be S1. > > > The reason why you can't enter ACPI S-states from CPUidle is because you > > need to go out of the idle loop to execute some ACPI-specific stuff. Which > > is not even specific to Intel chips, but to ACPI in general. > > The code was little tricky/unclean, but it "worked" for me at one > point... I called it "sleepy linux". Yes, you can find a system where it might kind of work (just because _PTS is empty or something like this). Is it going to work in general? No way. So please let's turn into something at least _theoretically_ viable. Thanks, Rafael -- 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
