linux-kernel - [PATCH] cpufreq: powernv: Remove global pstate ramp-down timer in POWER9

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Message-Id: <1524636895-27185-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com>
Date:   Wed, 25 Apr 2018 11:44:55 +0530
From:   Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
To:     rjw@...ysocki.net, viresh.kumar@...aro.org
Cc:     benh@...nel.crashing.org, mpe@...erman.id.au,
        linux-pm@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, svaidy@...ux.vnet.ibm.com,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
Subject: [PATCH] cpufreq: powernv: Remove global pstate ramp-down timer in POWER9

POWER9 doesnot support global pstate requests for the chip. So remove
the timer logic which slowly ramps down the global pstate in P9
platforms.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
---
 drivers/cpufreq/powernv-cpufreq.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 0591874..71f8682 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -750,8 +750,13 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 
 	cur_msec = jiffies_to_msecs(get_jiffies_64());
 
-	spin_lock(&gpstates->gpstate_lock);
 	freq_data.pstate_id = idx_to_pstate(new_index);
+	if (!gpstates) {
+		freq_data.gpstate_id = freq_data.pstate_id;
+		goto no_gpstate;
+	}
+
+	spin_lock(&gpstates->gpstate_lock);
 
 	if (!gpstates->last_sampled_time) {
 		gpstate_idx = new_index;
@@ -801,6 +806,7 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 
 	spin_unlock(&gpstates->gpstate_lock);
 
+no_gpstate:
 	/*
 	 * Use smp_call_function to send IPI and execute the
 	 * mtspr on target CPU.  We could do that without IPI
@@ -835,6 +841,13 @@ static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		kernfs_put(kn);
 	}
 
+	policy->freq_table = powernv_freqs;
+	policy->fast_switch_possible = true;
+
+	if (pvr_version_is(PVR_POWER9))
+		return 0;
+
+	/* Initialise Gpstate ramp-down timer only on POWER8 */
 	gpstates =  kzalloc(sizeof(*gpstates), GFP_KERNEL);
 	if (!gpstates)
 		return -ENOMEM;
@@ -849,15 +862,14 @@ static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
 				msecs_to_jiffies(GPSTATE_TIMER_INTERVAL);
 	spin_lock_init(&gpstates->gpstate_lock);
 
-	policy->freq_table = powernv_freqs;
-	policy->fast_switch_possible = true;
 	return 0;
 }
 
 static int powernv_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 {
 	/* timer is deleted in cpufreq_cpu_stop() */
-	kfree(policy->driver_data);
+	if (policy->driver_data)
+		kfree(policy->driver_data);
 
 	return 0;
 }
@@ -990,7 +1002,8 @@ static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
 	freq_data.pstate_id = idx_to_pstate(powernv_pstate_info.min);
 	freq_data.gpstate_id = idx_to_pstate(powernv_pstate_info.min);
 	smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
-	del_timer_sync(&gpstates->timer);
+	if (gpstates)
+		del_timer_sync(&gpstates->timer);
 }
 
 static unsigned int powernv_fast_switch(struct cpufreq_policy *policy,
-- 
1.8.3.1