From 92a3e426ec06e72b1c363179c79d30712447ff76 Mon Sep 17 00:00:00 2001
From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Date: Mon, 25 Mar 2019 09:04:40 -0700
Subject: [PATCH] cpufreq: intel_pstate: Also use CPPC nominal_perf for base_frequency
Git-commit: 92a3e426ec06e72b1c363179c79d30712447ff76
Patch-mainline: v5.1-rc3
References: bsc#1111666

The ACPI specification states that if the "Guaranteed Performance
Register" is not implemented, the OSPM assumes guaranteed performance
to always be equal to nominal performance.

So for invalid or unimplemented guaranteed performance register, use
nominal performance as guaranteed performance.

This change will fall back to nominal_perf when guranteed_perf is
invalid.  If nominal_perf is also invalid or not present, fall back
to the existing implementation, which is to read from HWP Capabilities
MSR.

Fixes: 86d333a8cc7f ("cpufreq: intel_pstate: Add base_frequency attribute")
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: 4.20+ <stable@vger.kernel.org> # 4.20+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/cpufreq/intel_pstate.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index e22f0dbaebb1..b599c7318aab 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -385,7 +385,10 @@ static int intel_pstate_get_cppc_guranteed(int cpu)
 	if (ret)
 		return ret;
 
-	return cppc_perf.guaranteed_perf;
+	if (cppc_perf.guaranteed_perf)
+		return cppc_perf.guaranteed_perf;
+
+	return cppc_perf.nominal_perf;
 }
 
 #else /* CONFIG_ACPI_CPPC_LIB */
-- 
2.16.4