cpufreq: amd-pstate: Update policy->cur in amd_pstate_adjust_perf()

Driver should update policy->cur after updating the frequency.
Currently amd_pstate doesn't update policy->cur when `adjust_perf`
is used. Which causes /proc/cpuinfo to show wrong cpu frequency.
Fix this by updating policy->cur with correct frequency value in
adjust_perf function callback.

- Before the fix: (setting min freq to 1.5 MHz)

[root@amd]# cat /proc/cpuinfo | grep "cpu MHz" | sort | uniq --count
      1 cpu MHz         : 1777.016
      1 cpu MHz         : 1797.160
      1 cpu MHz         : 1797.270
    189 cpu MHz         : 400.000

- After the fix: (setting min freq to 1.5 MHz)

[root@amd]# cat /proc/cpuinfo | grep "cpu MHz" | sort | uniq --count
      1 cpu MHz         : 1753.353
      1 cpu MHz         : 1756.838
      1 cpu MHz         : 1776.466
      1 cpu MHz         : 1776.873
      1 cpu MHz         : 1777.308
      1 cpu MHz         : 1779.900
    183 cpu MHz         : 1805.231
      1 cpu MHz         : 1956.815
      1 cpu MHz         : 2246.203
      1 cpu MHz         : 2259.984

Fixes: 1d215f0 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State")
Signed-off-by: Wyes Karny <wyes.karny@amd.com>
[ rjw: Subject edits ]
Cc: 5.17+ <stable@vger.kernel.org> # 5.17+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: wkarny

drivers/cpufreq/amd-pstate.c

@@ -501,12 +501,14 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
 				   unsigned long capacity)
 {
 	unsigned long max_perf, min_perf, des_perf,
-		      cap_perf, lowest_nonlinear_perf;
+		      cap_perf, lowest_nonlinear_perf, max_freq;
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 	struct amd_cpudata *cpudata = policy->driver_data;
+	unsigned int target_freq;
 
 	cap_perf = READ_ONCE(cpudata->highest_perf);
 	lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
+	max_freq = READ_ONCE(cpudata->max_freq);
 
 	des_perf = cap_perf;
 	if (target_perf < capacity)
@@ -523,6 +525,10 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
 	if (max_perf < min_perf)
 		max_perf = min_perf;
 
+	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
+	target_freq = div_u64(des_perf * max_freq, max_perf);
+	policy->cur = target_freq;
+
 	amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true,
 			policy->governor->flags);
 	cpufreq_cpu_put(policy);