cpufreq: intel_pstate: Adjust the .adjust_perf() driver callback

In some cases, the processor may not actually stick to the "desired"
performance level programmed through the driver's .adjust_perf()
callback and may go above it, which may not be desirable (for instance,
there may be a UCLAMP_MAX limit set for the task currently running on
the given CPU which should be respected).

Address that by adjusting the .adjust_perf() callback to take an
additional argument, max_perf, representing the maximum allowed
performance level of the CPU and update the intel_pstate driver to
take that argument into account as appropriate.

Accordingly, adjust cpufreq_driver_adjust_perf() and the other existing
user of .adjust_perf(), which is the amd-pstate driver (but the behavior
of that driver is not changed).

While at it, also update the cpufreq_driver_adjust_perf()
documentation to reflect this change and some previous code
changes that have not been taken into account in it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Link: https://patch.msgid.link/6277654.lOV4Wx5bFT@rafael.j.wysocki
[ rjw: Adjusted Rust function formatting ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index 58ac04c650a1..d624cccb6540 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -792,7 +792,13 @@ pub trait Driver {
     }
 
     /// Driver's `adjust_perf` callback.
-    fn adjust_perf(_policy: &mut Policy, _min_perf: usize, _target_perf: usize, _capacity: usize) {
+    fn adjust_perf(
+        _policy: &mut Policy,
+        _min_perf: usize,
+        _target_perf: usize,
+        _max_perf: usize,
+        _capacity: usize,
+    ) {
         build_error!(VTABLE_DEFAULT_ERROR)
     }
 
@@ -1263,12 +1269,13 @@ impl<T: Driver> Registration<T> {
         ptr: *mut bindings::cpufreq_policy,
         min_perf: c_ulong,
         target_perf: c_ulong,
+        max_perf: c_ulong,
         capacity: c_ulong,
     ) {
         // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the
         // lifetime of `policy`.
         let policy = unsafe { Policy::from_raw_mut(ptr) };
-        T::adjust_perf(policy, min_perf, target_perf, capacity);
+        T::adjust_perf(policy, min_perf, target_perf, max_perf, capacity);
     }
 
     /// Driver's `get_intermediate` callback.