On Thu, 2015-02-05 at 12:44 +0100, Thierry Reding wrote: > We've had some discussions about this internally and I think this should > not be a problem after all. The Tegra flow controller can be programmed > to automatically coordinate with the PMC to powergate CPUs when they > encounter a WFI instruction and unpowergate CPUs again when they are > woken up. With that in place the PMC registers don't need to be touched > anymore once the CPUs have been booted once. > > The solution that was discussed internally would involve having the > secure monitor (U-Boot's PSCI implementation in this case) program the > flow controller appropriately, point the CPU reset vectors to a location > containing a WFI instruction and power up the CPUs. That way they should > immediately be powergated when they reach the WFI instruction and the > PSCI implementation would then be able to wake them up without accessing > the PMC registers once the kernel has booted. > > Adding Peter. Please correct me if I misunderstood what we discussed. > Can you also provide Ian with pointers to the registers that need to be > programmed to make this work? I suspect that a lot of it can be gleaned > from the cpuidle drivers in arch/arm/mach-tegra in the upstream Linux > kernel.
Thanks, any *info would be good even though I could likely decode it from the driver... I'm afraid I've been a bit slack about updating the series with the other comments, mostly because I've been procrastinating over this powergate issue. Ian. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
