On Thu, 2012-12-06 at 06:18 +0800, Stephen Warren wrote: > On 12/05/2012 03:01 AM, Joseph Lo wrote: > > 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. The Tegra20 had a limition to > > power down both CPU cores. The secondary CPU must waits for CPU0 in > > powered-down state too. If the secondary CPU be woken up before CPU0 > > entering powered-down state, then it needs to restore its CPU states > > and waits for next chance. > > > > Be aware of that, you may see the legacy power state "LP2" in the code > > which is exactly the same meaning of "CPU power down". > > > diff --git a/arch/arm/mach-tegra/cpuidle-tegra20.c b/arch/arm/mach-tegra/cpuidle-tegra20.c > > > +static int __cpuinit tegra20_idle_lp2(struct cpuidle_device *dev, > > > + return (entered_lp2) ? index : 0; > > No need for the brackets there. > OK. Will fix. > BTW, could you Cc Colin Cross on any future revisions of these patches; > it'd be good to get his take on them. > OK. The next version will directly support coupled cpuidle. I will add Colin into Cc. > > diff --git a/arch/arm/mach-tegra/sleep-tegra20.S b/arch/arm/mach-tegra/sleep-tegra20.S > > > +/* > > + * tegra_pen_lock > > > + * on cpu 0: > > + * SCRATCH38 = r2 = flag[0] > > + * SCRATCH39 = r3 = flag[1] > > It would be slightly clearer if that was written: > > * r2 = flag[0] (in SCRATCH38) > * r3 = flag[1] (in SCRATCH39) > > since the meaning of r2/r3 is what's being selected. > OK. Will fix. > > + mov r12, #1 > > + str r12, [r2] @ flag[cpu] = 1 > > + dsb > > + str r12, [r1] @ !turn = cpu > > Should that be "str r0, [r1]"? Otherwise, you're always writing 1 there, > not writing the CPU ID as expected. The CPU_ID was not used to lock or un-lock the flag. Wriging 1 to lock and 0 to release. Thanks, Joseph -- 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
