linux-kernel - Re: Warning during suspend with MS-7310 mainboard

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Message-ID: <20090730164629.GC2593@redhat.com>
Date:	Thu, 30 Jul 2009 12:46:29 -0400
From:	Dave Jones <davej@...hat.com>
To:	"Langsdorf, Mark" <mark.langsdorf@....com>
Cc:	Eric Sesterhenn <eric.sesterhenn@...xperts.de>,
	linux-kernel@...r.kernel.org, cpufreq@...r.kernel.org,
	rusty@...tcorp.com.au
Subject: Re: Warning during suspend with MS-7310 mainboard

On Thu, Jul 30, 2009 at 11:38:22AM -0500, Langsdorf, Mark wrote:
 > I'll look into it.
 > 
 > First time I've had this bug reported, though.
 > 

It's happening because the suspend code runs with interrupts disabled,
and the powerpc workaround we do in the cpufreq suspend hook
calls the drivers ->get method.

powernow-k8's ->get does an smp_call_function_single
which needs interrupts enabled

If we just make the suspend code conditional on ppc, this whole problem
goes away.

Something like the patch below..

	Dave

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 5cc77fb..8d3b3d1 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1288,6 +1288,14 @@ static int cpufreq_suspend(struct sys_device *sysdev, pm_message_t pmsg)
 
 	dprintk("suspending cpu %u\n", cpu);
 
+	/*
+	 * This whole bogosity is here because Powerbooks are made of fail.
+	 * No sane platform should need any of the code below to be run.
+	 * (it's entirely the wrong thing to do, as driver->get may
+	 *  reenable interrupts on some architectures).
+	 */
+
+#ifdef __powerpc__
 	if (!cpu_online(cpu))
 		return 0;
 
@@ -1346,6 +1354,7 @@ static int cpufreq_suspend(struct sys_device *sysdev, pm_message_t pmsg)
 
 out:
 	cpufreq_cpu_put(cpu_policy);
+#endif	/* __powerpc__ */
 	return ret;
 }
 
@@ -1365,6 +1374,11 @@ static int cpufreq_resume(struct sys_device *sysdev)
 
 	dprintk("resuming cpu %u\n", cpu);
 
+	/* As with the ->suspend method, all the code below is
+	 * only necessary because Powerbooks suck.
+	 * See commit 42d4dc3f4e1e for jokes. */
+#ifdef __powerpc__
+
 	if (!cpu_online(cpu))
 		return 0;
 
@@ -1428,6 +1442,7 @@ out:
 	schedule_work(&cpu_policy->update);
 fail:
 	cpufreq_cpu_put(cpu_policy);
+#endif	/* __powerpc__ */
 	return ret;
 }
 
--
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