Re: [PATCH v5 2/5] powerpc/85xx: add HOTPLUG_CPU support

On Fri, Jun 01, 2012 at 04:27:27PM -0500, Scott Wood wrote:

On 05/11/2012 06:53 AM, Zhao Chenhui wrote:
\> +#if defined(CONFIG_FSL_BOOKE) || defined(CONFIG_6xx)

quoted

+extern void __flush_disable_L1(void);
+#endif

Prototypes aren't normally guarded by ifdefs.

OK. Thanks.

quoted

+static void __cpuinit smp_85xx_mach_cpu_die(void)
+{
+	unsigned int cpu = smp_processor_id();
+	u32 tmp;
+
+	local_irq_disable();
+	idle_task_exit();
+	generic_set_cpu_dead(cpu);
+	mb();
+
+	mtspr(SPRN_TCR, 0);
+
+	__flush_disable_L1();
+	tmp = (mfspr(SPRN_HID0) & ~(HID0_DOZE|HID0_SLEEP)) | HID0_NAP;
+	mtspr(SPRN_HID0, tmp);
+
+	/* Enter NAP mode. */
+	tmp = mfmsr();
+	tmp |= MSR_WE;
+	mb();
+	mtmsr(tmp);
+	isync();

Need isync after writing to HID0.

quoted

+		/*
+		 * We don't set the BPTR register here upon it points
+		 * to the boot page properly.
+		 */
+		mpic_reset_core(hw_cpu);

That comment's wording is hard to follow -- maybe s/upon it points/since
it already points/

quoted

+		/* wait until core is ready... */
+		if (!spin_event_timeout(in_be32(&spin_table->addr_l) == 1,
+						10000, 100)) {
+			pr_err("%s: timeout waiting for core %d to reset\n",
+							__func__, hw_cpu);
+			ret = -ENOENT;
+			goto out;
+		}

We need to fix U-Boot to write addr_l last (with an msync beforehand).

I agree.

quoted

-#ifdef CONFIG_KEXEC
+#if defined(CONFIG_KEXEC) || defined(CONFIG_HOTPLUG_CPU)

Let's not grow lists like this.  Is there any harm in building it
unconditionally?

-Scott

We need this ifdef. We only set give_timebase/take_timebase
when CONFIG_KEXEC or CONFIG_HOTPLUG_CPU is defined.

-Chenhui