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. > > I'd like Peter to review this too (CC'd). I guess it looks OK... > > > diff --git a/arch/arm/mach-tegra/platsmp.c b/arch/arm/mach-tegra/platsmp.c > > > @@ -72,7 +75,27 @@ static int tegra30_power_up_cpu(unsigned int cpu) > > if (pwrgateid < 0) > > return pwrgateid; > > > > - /* If this is the first boot, toggle powergates directly. */ > > + /* > > + * If the CPU had booted and went through here after CPU > > + * had been already un-gated by flow controller. Wait > > + * for confirmation that the CPU is powered then remove > > + * the IO clamps. On the cold boot entry, do not wait. > > + */ > > That comment is quite unclear. In particular the first sentence says "if > something" rather than "if something then something". Can you please > re-write it? > OK. > 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.
Thanks, Joseph -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
