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

Gautham R. Shenoy
2025-10-15T08:46:53Z

On Thu, Oct 09, 2025 at 11:17:51AM -0500, Mario Limonciello (AMD) wrote:
> Rather than scanning the buffer and manually matching the string
> use the sysfs macros.
>
> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>

The patch looks good to me.
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>

> ---
> 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
>

--
Thanks and Regards
gautham.