From: Bhavana Nagendra <bnagendr@redhat.com>
Subject: Re: [RHEL5.1 REGRESSION] Fix tscsync frequency transitions
Date: Thu, 26 Jul 2007 13:42:43 -0400
Bugzilla: 245082
Message-Id: <46A8DD13.7060009@redhat.com>
Changelog: [x86] Fix tscsync frequency transitions

Resolves BZ 245082

The Power Now! driver has a module parameter "tscsync" which needs to be set
if TSC is used as a time source. This allows the cores to change frequencies
in step and avoids the skew.  A regression was found wherein the req_state
data structure was not initialized correctly.

Testing has confirmed that this patch works on mutilple AMD platforms and
is upstream.  

--- linux-2.6.18.i386/arch/i386/kernel/cpu/cpufreq/powernow-k8.c.porig	2007-07-25 16:55:30.000000000 -0400
+++ linux-2.6.18.i386/arch/i386/kernel/cpu/cpufreq/powernow-k8.c	2007-07-26 11:19:16.000000000 -0400
@@ -1276,9 +1276,6 @@ static int __cpuinit powernowk8_cpu_init
 	if (cpu_family == CPU_OPTERON)
 		fidvid_msr_init();
 
-	if (tscsync && (cpu_family == CPU_OPTERON))
-		req_state[pol->cpu] = 0;
-
 	/* run on any CPU again */
 	set_cpus_allowed(current, oldmask);
 
@@ -1427,6 +1424,9 @@ static int __cpuinit powernowk8_init(voi
 				printk(KERN_ERR PFX "Unable to allocate memory!\n");
 				return -ENOMEM;
 			}
+			/* necessary for dual-cores (99=just a large number) */
+			for(i=0; i < num_possible_cpus(); i++)
+				req_state[i] = 99;
 		}
 		printk(KERN_INFO PFX "Found %d %s "
 			"processors (%d cpu cores) (" VERSION ")\n", supported_cpus/cpu_data[0].booted_cores,