[LTP] cpufreq.c: add new test for cpufreq sysfs interface validation

[linuxtestproject.agent@gmail.com]

Hi Piotr,

On Tue, 05 May 2026 11:48:54 +0200, Piotr Kubaj wrote:
> cpufreq.c: add new test for cpufreq sysfs interface validation
>
> Runs various sanity checks for intel_pstate cpufreq sysfs interface.
>
> Checks whether intel_pstate driver is used, whether it is possible
> to switch scaling_governor to powersave and performance,
> whether it is possible to disable turbo frequency and
> whether it is possible to change scaling_min_freq and scaling_max_freq
> to its minimal valid and maximal valid values.

The body only describes what the test does, not why it is needed. Add a
sentence stating the motivation — e.g. lack of regression coverage for the
intel_pstate sysfs interface, or a specific issue that prompted this test.

Pre-existing issues noticed in the surrounding code (not introduced
by this patch):

- cpufreq.c:19 — `static char path[PATH_MAX]` used as a shared scratch
  buffer across setup/run/cleanup; a function-local buffer in run() would
  be cleaner.

---
Note:

Our agent completed the review of the patch. The full review can be
found at: https://github.com/linux-test-project/ltp-agent/actions/runs/25371830221

The agent can sometimes produce false positives although often its
findings are genuine. If you find issues with the review, please
comment this email or ignore the suggestions.

Regards,
LTP AI Reviewer