linux-kernel - [PATCH] amd-pstate: Only print supported epp values for performance governor

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Message-ID: <20230925065818.1502-1-ayush.jain3@amd.com>
Date:   Mon, 25 Sep 2023 12:28:18 +0530
From:   Ayush Jain <ayush.jain3@....com>
To:     <rafael@...nel.org>, <viresh.kumar@...aro.org>,
        <Mario.Limonciello@....com>, <wyes.karny@....com>,
        <Perry.Yuan@....com>
CC:     <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <santosh.shukla@....com>, Ayush Jain <ayush.jain3@....com>
Subject: [PATCH] amd-pstate: Only print supported epp values for performance governor

show_energy_performance_available_preferences() to show only supported
values which is performance in performance governor policy.

-------Before--------
$ cat /sys/devices/system/cpu/cpu1/cpufreq/scaling_driver
amd-pstate-epp
$ cat /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor
performance
$ cat /sys/devices/system/cpu/cpu1/cpufreq/energy_performance_preference
performance
$ cat /sys/devices/system/cpu/cpu1/cpufreq/energy_performance_available_preferences
default performance balance_performance balance_power power

-------After--------
$ cat /sys/devices/system/cpu/cpu1/cpufreq/scaling_driver
amd-pstate-epp
$ cat /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor
performance
$ cat /sys/devices/system/cpu/cpu1/cpufreq/energy_performance_preference
performance
$ cat /sys/devices/system/cpu/cpu1/cpufreq/energy_performance_available_preferences
performance

Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
Suggested-by: Wyes Karny <wyes.karny@....com>
Signed-off-by: Ayush Jain <ayush.jain3@....com>
Reviewed-by: Wyes Karny <wyes.karny@....com>

---
Changes v1->v2
* Fixed spacebar and spelling issues
* Using EPP_INDEX_PERFORMANCE instead of hardcoding index 1
* collected reviewed-by
---
 drivers/cpufreq/amd-pstate.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 9a1e194d5cf8..469461937fb6 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -850,11 +850,15 @@ static ssize_t show_energy_performance_available_preferences(
 {
 	int i = 0;
 	int offset = 0;
+	struct amd_cpudata *cpudata = policy->driver_data;
+
+	if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
+		return sysfs_emit_at(buf, offset, "%s\n", energy_perf_strings[EPP_INDEX_PERFORMANCE]);
 
 	while (energy_perf_strings[i] != NULL)
 		offset += sysfs_emit_at(buf, offset, "%s ", energy_perf_strings[i++]);
 
-	sysfs_emit_at(buf, offset, "\n");
+	offset += sysfs_emit_at(buf, offset, "\n");
 
 	return offset;
 }
-- 
2.34.1