From bb7fadf4a86e19b52cbe850c9274bfa643d3ce52 Mon Sep 17 00:00:00 2001 From: Mario Limonciello Date: Wed, 26 Feb 2025 01:49:28 -0600 Subject: cpufreq/amd-pstate: Cache CPPC request in shared mem case too In order to prevent a potential write for shmem_update_perf() cache the request into the cppc_req_cached variable normally only used for the MSR case. This adds symmetry into the code and potentially avoids extra writes. Reviewed-by: Dhananjay Ugwekar Reviewed-by: Gautham R. Shenoy Signed-off-by: Mario Limonciello --- drivers/cpufreq/amd-pstate.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -496,6 +496,8 @@ static int shmem_update_perf(struct amd_ u8 des_perf, u8 max_perf, u8 epp, bool fast_switch) { struct cppc_perf_ctrls perf_ctrls; + u64 value, prev; + int ret; if (cppc_state == AMD_PSTATE_ACTIVE) { int ret = shmem_set_epp(cpudata, epp); @@ -504,11 +506,29 @@ static int shmem_update_perf(struct amd_ return ret; } + value = prev = READ_ONCE(cpudata->cppc_req_cached); + + value &= ~(AMD_CPPC_MAX_PERF_MASK | AMD_CPPC_MIN_PERF_MASK | + AMD_CPPC_DES_PERF_MASK | AMD_CPPC_EPP_PERF_MASK); + value |= FIELD_PREP(AMD_CPPC_MAX_PERF_MASK, max_perf); + value |= FIELD_PREP(AMD_CPPC_DES_PERF_MASK, des_perf); + value |= FIELD_PREP(AMD_CPPC_MIN_PERF_MASK, min_perf); + value |= FIELD_PREP(AMD_CPPC_EPP_PERF_MASK, epp); + + if (value == prev) + return 0; + perf_ctrls.max_perf = max_perf; perf_ctrls.min_perf = min_perf; perf_ctrls.desired_perf = des_perf; - return cppc_set_perf(cpudata->cpu, &perf_ctrls); + ret = cppc_set_perf(cpudata->cpu, &perf_ctrls); + if (ret) + return ret; + + WRITE_ONCE(cpudata->cppc_req_cached, value); + + return 0; } static inline bool amd_pstate_sample(struct amd_cpudata *cpudata)