On 12/21/2012 01:07 AM, Joseph Lo wrote: > On Fri, 2012-12-21 at 00:55 +0800, Stephen Warren wrote: >> On 12/19/2012 07:30 PM, Joseph Lo wrote: >>> The power up sequence is different on the cold boot CPU and the CPU >>> that resumed from the hotplug. For the cold boot CPU, it was been power >>> gated as default. To power up the cold boot CPU, the power should be >>> un-gated by un toggling the power gate register manually. >>> >>> For the CPU that resumed from the hotplug, after un-halted the CPU. The >>> flow controller will un-gate the power of the CPU. No need to manually >>> control, just wait the power be resumed and continue the power up >>> sequence after the CPU power is ready. ... >> Also, it'd be good to explain (or at least briefly reference) the boot >> path for a cold-boot CPU and a warm boot CPU; I assume that somehow a >> cold boot CPU doesn't execute tegra_secondary_init(), but a warm boot >> CPU does? >> > The boot path was the same. Both of the conditions were booted from > tegra_boot_secondary. Just the power sequence has been different. We add > the code to recover the power up sequence of warm boot CPU. Ah, I see - tegra20_power_up_cpu() runs first to boot the secondary CPU, and tegra_secondary_init() runs on the secondary CPU during the boot process, which then sets tegra_cpu_init_mask which influences what tegra20_power_up_cpu() does next time around. It'd be useful to say that in the patch description. -- 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
