On Fri, Sep 26, 2014 at 01:20:04PM +0100, Russell King - ARM Linux wrote:

On Fri, Sep 26, 2014 at 07:25:01PM +0800, Chenhui Zhao wrote:

quoted

+static inline void ls1_do_lowpower(unsigned int cpu, int *spurious)
+{
+	/*
+	 * there is no power-control hardware on this platform, so all
+	 * we can do is put the core into WFI; this is safe as the calling
+	 * code will have already disabled interrupts
+	 */
+	for (;;) {
+		wfi();
+
+		if (pen_release == cpu_logical_map(cpu)) {
+			/*OK, proper wakeup, we're done*/
+			break;
+		}
+
+		/*
+		 * Getting here, means that we have come out of WFI without
+		 * having been woken up - this shouldn't happen
+		 *
+		 * Just note it happening - when we're woken, we can report
+		 * its occurrence.
+		 */
+		(*spurious)++;
+	}
+}

This is pretty much unacceptable - this breaks kexec(), and suspend
support because your secondary CPUs aren't really sleeping, they're
sitting in a loop doing nothing.

Agreed.

This looks to be a carbon copy of the vexpress pseudo-hotplug in
arch/arm/mach-vexpress/hotplug.c, which is obviously broken in the way
you describe above. Perhaps we should go about ripping that out?

Mark.