On Fri, Aug 29, 2014 at 04:06:40AM +0100, Huang Tao wrote: > Hi, Mark: Hi, > 在 2014年08月28日 23:11, Mark Rutland 写道: > > To clarify: if there are low power states that the CPU can enter where > > we lose state, then this patch isn't correct. > Right now, the software of RK3288 SoC only support CPU hotplug > (cpu_on/off) and power off all CPUs on suspend. Sure, but that's a Linux implementation detail rather than a fixed property of the hardware. Given those states exist, the "always-on" property is not appropriate. > We do not implement cpuidle to power off CPU. Do you think we should > introduce a broadcast timer? If one is present, yes. > On our early kernel, I never see any interrupt on a broadcast timer > (yes, we implement it with a external timer). That's fine; Linux doesn't need to use it just yet. However, when we want to use low power states later, it will be necessary to enable placing all CPUS into a low power state. If your external timer is already supported by an existing driver, there is no reason not to add it now. > > A more general approach would be to enable the broadcast hrtimer for > > arm, as has been done for arm64. > Yes. I think it should be done by arm framework. Patches welcome. I also think it would make sense to enable this for arm. Thanks, Mark. -- 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
