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-rw-r--r--arch/x86/kernel/cpu/cpufreq/powernow-k8.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
index cf52215d9eb1..935989693a64 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
@@ -1046,6 +1046,19 @@ static int get_transition_latency(struct powernow_k8_data *data)
if (cur_latency > max_latency)
max_latency = cur_latency;
}
+ if (max_latency == 0) {
+ /*
+ * Fam 11h always returns 0 as transition latency.
+ * This is intended and means "very fast". While cpufreq core
+ * and governors currently can handle that gracefully, better
+ * set it to 1 to avoid problems in the future.
+ * For all others it's a BIOS bug.
+ */
+ if (!boot_cpu_data.x86 == 0x11)
+ printk(KERN_ERR FW_WARN PFX "Invalid zero transition "
+ "latency\n");
+ max_latency = 1;
+ }
/* value in usecs, needs to be in nanoseconds */
return 1000 * max_latency;
}