cpufreq: intel_pstate: Use CPU load based algorithm for PM_MOBILE

Use get_target_pstate_use_cpu_load() to calculate target P-State for
devices, with the preferred power management profile in ACPI FADT
set to PM_MOBILE.

This may help in resolving some thermal issues caused by low sustained
cpu bound workloads. The current algorithm tend to over provision in this
case as it doesn't look at the CPU busyness.

Also included the fix from Arnd Bergmann <arnd@arndb.de> to solve compile
issue, when CONFIG_ACPI is not defined.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -1771,6 +1771,19 @@ static void __init copy_pid_params(struct pstate_adjust_policy *policy)
 	pid_params.setpoint = policy->setpoint;
 }
 
+#ifdef CONFIG_ACPI
+static void intel_pstate_use_acpi_profile(void)
+{
+	if (acpi_gbl_FADT.preferred_profile == PM_MOBILE)
+		pstate_funcs.get_target_pstate =
+				get_target_pstate_use_cpu_load;
+}
+#else
+static void intel_pstate_use_acpi_profile(void)
+{
+}
+#endif
+
 static void __init copy_cpu_funcs(struct pstate_funcs *funcs)
 {
 	pstate_funcs.get_max   = funcs->get_max;
@@ -1782,6 +1795,7 @@ static void __init copy_cpu_funcs(struct pstate_funcs *funcs)
 	pstate_funcs.get_vid   = funcs->get_vid;
 	pstate_funcs.get_target_pstate = funcs->get_target_pstate;
 
+	intel_pstate_use_acpi_profile();
 }
 
 #ifdef CONFIG_ACPI