[PATCH v2 1/6] cpufreq/amd-pstate: Use sysfs_match_string() for epp

Mario Limonciello (AMD)
2025-10-09T16:18:05Z

Rather than scanning the buffer and manually matching the string
use the sysfs macros.

Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
v2:
* Drop NULL from energy_perf_strings too (Gautham)
---
drivers/cpufreq/amd-pstate.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index b44f0f7a5ba1c..0bc5013448873 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -118,7 +118,6 @@ static const char * const energy_perf_strings[] = {
[EPP_INDEX_BALANCE_PERFORMANCE] = "balance_performance",
[EPP_INDEX_BALANCE_POWERSAVE] = "balance_power",
[EPP_INDEX_POWERSAVE] = "power",
- NULL
};

static unsigned int epp_values[] = {
@@ -1137,16 +1136,15 @@ static ssize_t show_amd_pstate_hw_prefcore(struct cpufreq_policy *policy,
static ssize_t show_energy_performance_available_preferences(
struct cpufreq_policy *policy, char *buf)
{
- int i = 0;
- int offset = 0;
+ int offset = 0, i;
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++]);
+ for (i = 0; i < ARRAY_SIZE(energy_perf_strings); i++)
+ offset += sysfs_emit_at(buf, offset, "%s ", energy_perf_strings[i]);

offset += sysfs_emit_at(buf, offset, "\n");

@@ -1157,15 +1155,10 @@ static ssize_t store_energy_performance_preference(
struct cpufreq_policy *policy, const char *buf, size_t count)
{
struct amd_cpudata *cpudata = policy->driver_data;
- char str_preference[21];
ssize_t ret;
u8 epp;

- ret = sscanf(buf, "%20s", str_preference);
- if (ret != 1)
- return -EINVAL;
-
- ret = match_string(energy_perf_strings, -1, str_preference);
+ ret = sysfs_match_string(energy_perf_strings, buf);
if (ret < 0)
return -EINVAL;

--
2.43.0