cpufreq/amd-pstate: Overhaul locking

amd_pstate_cpu_boost_update() and refresh_frequency_limits() both
update the policy state and have nothing to do with the amd-pstate
driver itself.

A global "limits" lock doesn't make sense because each CPU can have
policies changed independently.  Each time a CPU changes values they
will atomically be written to the per-CPU perf member. Drop per CPU
locking cases.

The remaining "global" driver lock is used to ensure that only one
entity can change driver modes at a given time.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 983c8728701e5515c00ba2a1781ffb51b3e69246..65714d510ce35b1fcf862db1635b3d1d604a1ef6 100644 (file)
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -196,7 +196,6 @@ static inline int get_mode_idx_from_str(const char *str, size_t size)
        return -EINVAL;
 }
 
-static DEFINE_MUTEX(amd_pstate_limits_lock);
 static DEFINE_MUTEX(amd_pstate_driver_lock);
 
 static u8 msr_get_epp(struct amd_cpudata *cpudata)
@@ -752,7 +751,6 @@ static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state)
                pr_err("Boost mode is not supported by this processor or SBIOS\n");
                return -EOPNOTSUPP;
        }
-       guard(mutex)(&amd_pstate_driver_lock);
 
        ret = amd_pstate_cpu_boost_update(policy, state);
        refresh_frequency_limits(policy);
@@ -1170,8 +1168,6 @@ static ssize_t store_energy_performance_preference(
        if (ret < 0)
                return -EINVAL;
 
-       guard(mutex)(&amd_pstate_limits_lock);
-
        ret = amd_pstate_set_energy_pref_index(policy, ret);
 
        return ret ? ret : count;
@@ -1344,8 +1340,10 @@ int amd_pstate_update_status(const char *buf, size_t size)
        if (mode_idx < 0 || mode_idx >= AMD_PSTATE_MAX)
                return -EINVAL;
 
-       if (mode_state_machine[cppc_state][mode_idx])
+       if (mode_state_machine[cppc_state][mode_idx]) {
+               guard(mutex)(&amd_pstate_driver_lock);
                return mode_state_machine[cppc_state][mode_idx](mode_idx);
+       }
 
        return 0;
 }
@@ -1366,7 +1364,6 @@ static ssize_t status_store(struct device *a, struct device_attribute *b,
        char *p = memchr(buf, '\n', count);
        int ret;
 
-       guard(mutex)(&amd_pstate_driver_lock);
        ret = amd_pstate_update_status(buf, p ? p - buf : count);
 
        return ret < 0 ? ret : count;
@@ -1638,8 +1635,6 @@ static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
        if (cpudata->suspended)
                return 0;
 
-       guard(mutex)(&amd_pstate_limits_lock);
-
        if (trace_amd_pstate_epp_perf_enabled()) {
                trace_amd_pstate_epp_perf(cpudata->cpu, perf.highest_perf,
                                          AMD_CPPC_EPP_BALANCE_POWERSAVE,
@@ -1679,8 +1674,6 @@ static int amd_pstate_epp_resume(struct cpufreq_policy *policy)
        struct amd_cpudata *cpudata = policy->driver_data;
 
        if (cpudata->suspended) {
-               guard(mutex)(&amd_pstate_limits_lock);
-
                /* enable amd pstate from suspend state*/
                amd_pstate_epp_reenable(policy);