From da5e79bc70b84971d2b3a55fb252e34e51d81d48 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Mon, 15 Oct 2018 23:21:05 +0200
Subject: [PATCH] cpufreq: conservative: Take limits changes into account properly
Git-commit: da5e79bc70b84971d2b3a55fb252e34e51d81d48
Patch-mainline: v4.20-rc1
References: bsc#1051510

If the policy limits change between invocations of cs_dbs_update(),
the requested frequency value stored in dbs_info may not be updated
and the function may use a stale value of it next time.  Moreover, if
idle periods are takem into account by cs_dbs_update(), the requested
frequency value stored in dbs_info may be below the min policy limit,
which is incorrect.

To fix these problems, always update the requested frequency value
in dbs_info along with the local copy of it when the previous
requested frequency is beyond the policy limits and avoid decreasing
the requested frequency below the min policy limit when taking
idle periods into account.

Fixes: abb6627910a1 (cpufreq: conservative: Fix next frequency selection)
Fixes: 00bfe05889e9 (cpufreq: conservative: Decrease frequency faster for deferred updates)
Reported-by: Waldemar Rymarkiewicz <waldemarx.rymarkiewicz@intel.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Waldemar Rymarkiewicz <waldemarx.rymarkiewicz@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/cpufreq/cpufreq_conservative.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index f20f20a77d4d..4268f87e99fc 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -80,8 +80,10 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 	 * changed in the meantime, so fall back to current frequency in that
 	 * case.
 	 */
-	if (requested_freq > policy->max || requested_freq < policy->min)
+	if (requested_freq > policy->max || requested_freq < policy->min) {
 		requested_freq = policy->cur;
+		dbs_info->requested_freq = requested_freq;
+	}
 
 	freq_step = get_freq_step(cs_tuners, policy);
 
@@ -92,7 +94,7 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 	if (policy_dbs->idle_periods < UINT_MAX) {
 		unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
 
-		if (requested_freq > freq_steps)
+		if (requested_freq > policy->min + freq_steps)
 			requested_freq -= freq_steps;
 		else
 			requested_freq = policy->min;
-- 
2.16.4