On 01/16/2013 07:30 PM, Joseph Lo wrote: > On Thu, 2013-01-17 at 05:31 +0800, Stephen Warren wrote: >> On 01/16/2013 11:55 AM, Colin Cross wrote: >>> On Wed, Jan 16, 2013 at 12:11 AM, Joseph Lo <josephl@xxxxxxxxxx> wrote: >>>> The "powered-down" cpuidle mode of Tegra20 needs the CPU0 be the last one >>>> core to go into this mode before other core. The coupled cpuidle framework >>>> can help to sync the MPCore to coupled state then go into "powered-down" >>>> idle mode together. The driver can just assume the MPCore come into >>>> "powered-down" mode at the same time. No need to take care if the CPU_0 >>>> goes into this mode along and only can put it into safe idle mode (WFI). >>>> >>>> The powered-down state of Tegra20 requires power gating both CPU cores. >>>> When the secondary CPU requests to enter powered-down state, it saves >>>> its own contexts and then enters WFI for waiting CPU0 in the same state. >>>> When the CPU0 requests powered-down state, it attempts to put the secondary >>>> CPU into reset to prevent it from waking up. Then power down both CPUs >>>> together and power off the cpu rail. >>>> >>>> Be aware of that, you may see the legacy power state "LP2" in the code >> >> Colin, since you only raised a few small issues on this series, does >> that mean you're OK with it once those issues are fixed? >> >> Joseph, we'll be merging Tegra114 in the near future. How will this >> patch series affect Tegra114? Will the cpuidle driver simply fail to >> register on Tegra114 (which would be fine until we explicitly add >> support), or would we need to disable cpuidle in Kconfig to get a >> working Tegra114 kernel. Does this patch series affect the answer to the >> previous question? Thanks. >> > Stephen, > > This patch series won't affect Tegra114. I think I need to add a simple > cpuidle driver for Tegra114 to support just WFI state first. Ah right, I see that tegra_cpuidle_init() already switches on the SoC version and doesn't do anything for unknown SoCs. > And I am going do some re-works about CPUs and cluster power status sync > functions that be introduced recently[1] for CPU hotplug, idle and > secondary booting in Tegra tree. I hope I can hide all the power related > function behind that and make the CPU idle driver be more generic for > all Tegra series. > > Before that re-works, I will still keep upstream the platform suspend > function for Tegra. > (If I am not in the right direction, please pull me back.) That's all fine; I just wanted to make sure that applying these patches wouldn't break anything in the new Tegra114 support. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
