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. 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.) Thanks, Joseph [1]: https://patchwork.kernel.org/patch/1957891/ https://patchwork.kernel.org/patch/1957951/ (pretty good job by Nicolas and Dave) -- 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
