cpufreq: intel_pstate: Fix intel_pstate_get_hwp_max() for turbo disabled

This fixes the behavior of the scaling_max_freq and scaling_min_freq
sysfs files in systems which had turbo disabled by the BIOS.

Caleb noticed that the HWP is programmed to operate in the wrong
P-state range on his system when the CPUFREQ policy min/max frequency
is set via sysfs.  This seems to be because in his system
intel_pstate_get_hwp_max() is returning the maximum turbo P-state even
though turbo was disabled by the BIOS, which causes intel_pstate to
scale kHz frequencies incorrectly e.g. setting the maximum turbo
frequency whenever the maximum guaranteed frequency is requested via
sysfs.
Tested-by: Caleb Callaway <caleb.callaway@intel.com>
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Minor subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -836,7 +836,7 @@ static void intel_pstate_get_hwp_max(unsigned int cpu, int *phy_max,
 
 	rdmsrl_on_cpu(cpu, MSR_HWP_CAPABILITIES, &cap);
 	WRITE_ONCE(all_cpu_data[cpu]->hwp_cap_cached, cap);
-	if (global.no_turbo)
+	if (global.no_turbo || global.turbo_disabled)
 		*current_max = HWP_GUARANTEED_PERF(cap);
 	else
 		*current_max = HWP_HIGHEST_PERF(cap);