On Tue, 15 Jan 2013, Joseph Lo wrote: > On Mon, 2013-01-14 at 22:05 +0800, Nicolas Pitre wrote: > > On Mon, 14 Jan 2013, Joseph Lo wrote: > > > > > Hi Nicolas, > > > > > > On Thu, 2013-01-10 at 08:20 +0800, Nicolas Pitre wrote: > > > > This is the initial public posting of the initial support for big.LITTLE. > > > > Included here is the code required to safely power up and down CPUs in a > > > > b.L system, whether this is via CPU hotplug, a cpuidle driver or the > > > > Linaro b.L in-kernel switcher[*] on top of this. Only SMP secondary > > > > boot and CPU hotplug support is included at this time. Getting to this > > > > point already represents a significcant chunk of code as illustrated by > > > > the diffstat below. > > > > > > > > > > > > > > Thanks for introducing this series. > > > I am taking a look at this series. It introduced an algorithm for > > > syncing and avoid racing when syncing the power status of clusters and > > > CPUs. Do you think these codes could have a chance to become a generic > > > framework? > > > > Yes. As I mentioned before, the bL_ prefix is implied only by the fact > > that big.LITTLE was the motivation for creating this code. > > > > > The Tegra chip series had a similar design for CPU clusters and it > > had > > > limitation that the CPU0 always needs to be the last CPU to be shut down > > > before cluster power down as well. I believe it can also get benefits of > > > this works. We indeed need a similar algorithm to sync CPUs power status > > > before cluster power down and switching. > > > > > > The "bL_entry.c", "bL_entry.S", "bL_entry.h", "vlock.h" and "vlock.S" > > > looks have a chance to be a common framework for ARM platform even if it > > > just support one cluster. Because some systems had the limitations for > > > cluster power down. That's why the coupled cpuidle been introduced. And > > > this framework could be enabled automatically if platform dependent or > > > by menuconfig. > > > > Absolutely. > > > So do you have a plan to make it become a generic framework in this > series or later work? It is already generic, except for the name. In other words, you could start using this code already. I'm still debating a good substitute for the bL_ prefix in this series to give it the appearance of generic code. > (And I will add some common power sync wrapper functions that based on > this framework for all Tegra series.) Great! Nicolas -- 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
