IPS driver: don't toggle CPU turbo on unsupported CPUs

If the CPU doesn't support turbo, don't try to enable/disable it.

http://bugzilla.kernel.org/show_bug.cgi?id=18742

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/intel_ips.c

@@ -51,7 +51,6 @@
  * TODO:
  *   - handle CPU hotplug
  *   - provide turbo enable/disable api
- *   - make sure we can write turbo enable/disable reg based on MISC_EN
  *
  * Related documents:
  *   - CDI 403777, 403778 - Auburndale EDS vol 1 & 2
@@ -325,6 +324,7 @@ struct ips_driver {
 	bool gpu_preferred;
 	bool poll_turbo_status;
 	bool second_cpu;
+	bool turbo_toggle_allowed;
 	struct ips_mcp_limits *limits;
 
 	/* Optional MCH interfaces for if i915 is in use */
@@ -461,7 +461,8 @@ static void ips_enable_cpu_turbo(struct ips_driver *ips)
 	if (ips->__cpu_turbo_on)
 		return;
 
-	on_each_cpu(do_enable_cpu_turbo, ips, 1);
+	if (ips->turbo_toggle_allowed)
+		on_each_cpu(do_enable_cpu_turbo, ips, 1);
 
 	ips->__cpu_turbo_on = true;
 }
@@ -498,7 +499,8 @@ static void ips_disable_cpu_turbo(struct ips_driver *ips)
 	if (!ips->__cpu_turbo_on)
 		return;
 
-	on_each_cpu(do_disable_cpu_turbo, ips, 1);
+	if (ips->turbo_toggle_allowed)
+		on_each_cpu(do_disable_cpu_turbo, ips, 1);
 
 	ips->__cpu_turbo_on = false;
 }
@@ -1332,8 +1334,10 @@ static struct ips_mcp_limits *ips_detect_cpu(struct ips_driver *ips)
 	 * turbo manually or we'll get an illegal MSR access, even though
 	 * turbo will still be available.
 	 */
-	if (!(misc_en & IA32_MISC_TURBO_EN))
-		; /* add turbo MSR write allowed flag if necessary */
+	if (misc_en & IA32_MISC_TURBO_EN)
+		ips->turbo_toggle_allowed = true;
+	else
+		ips->turbo_toggle_allowed = false;
 
 	if (strstr(boot_cpu_data.x86_model_id, "CPU       M"))
 		limits = &ips_sv_limits;