[PATCH 3/3] ACPI: CPPC: Evaluate performance-control PCC use once

[Christian Loehle]

cppc_set_perf() evaluates the same immutable address-space predicates
before and after each phase of a performance-control update. This repeats
the three-control PCC test three times for every target request.

Evaluate the predicate once after resolving the control descriptors and
reuse the result throughout the transaction.

Signed-off-by: Christian Loehle <christian.loehle@xxxxxxx>
---
 drivers/acpi/cppc_acpi.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 2793d6b7d40d..cd1c4a30eb6f 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -2002,6 +2002,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	struct cpc_register_resource *desired_reg, *min_perf_reg, *max_perf_reg;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 	struct cppc_pcc_data *pcc_ss_data = NULL;
+	bool regs_in_pcc;
 	int ret = 0;
 
 	if (!cpc_desc) {
@@ -2012,6 +2013,8 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
 	min_perf_reg = &cpc_desc->cpc_regs[MIN_PERF];
 	max_perf_reg = &cpc_desc->cpc_regs[MAX_PERF];
+	regs_in_pcc = CPC_IN_PCC(desired_reg) || CPC_IN_PCC(min_perf_reg) ||
+		      CPC_IN_PCC(max_perf_reg);
 
 	/*
 	 * This is Phase-I where we want to write to CPC registers
@@ -2020,7 +2023,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	 * Since read_lock can be acquired by multiple CPUs simultaneously we
 	 * achieve that goal here
 	 */
-	if (CPC_IN_PCC(desired_reg) || CPC_IN_PCC(min_perf_reg) || CPC_IN_PCC(max_perf_reg)) {
+	if (regs_in_pcc) {
 		if (pcc_ss_id < 0) {
 			pr_debug("Invalid pcc_ss_id\n");
 			return -ENODEV;
@@ -2056,7 +2059,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	if (perf_ctrls->max_perf && CPC_SUPPORTED(max_perf_reg))
 		cpc_write(cpu, max_perf_reg, perf_ctrls->max_perf);
 
-	if (CPC_IN_PCC(desired_reg) || CPC_IN_PCC(min_perf_reg) || CPC_IN_PCC(max_perf_reg))
+	if (regs_in_pcc)
 		up_read(&pcc_ss_data->pcc_lock);	/* END Phase-I */
 	/*
 	 * This is Phase-II where we transfer the ownership of PCC to Platform
@@ -2104,7 +2107,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
 	 * case during a CMD_READ and if there are pending writes it delivers
 	 * the write command before servicing the read command
 	 */
-	if (CPC_IN_PCC(desired_reg) || CPC_IN_PCC(min_perf_reg) || CPC_IN_PCC(max_perf_reg)) {
+	if (regs_in_pcc) {
 		if (down_write_trylock(&pcc_ss_data->pcc_lock)) {/* BEGIN Phase-II */
 			/* Update only if there are pending write commands */
 			if (pcc_ss_data->pending_pcc_write_cmd)
-- 
2.34.1