[PATCH v3 1/6] acpi: cppc: Add min and max perf reg writing support

Wyes Karny
2023-01-19T11:51:25Z

Currently writing of min and max perf register is deferred in
cppc_set_perf function. In CPPC guided mode, these registers needed to
be written to guide the platform about min and max perf levels. Add this support
to make guided mode work properly on AMD shared memory systems.

Signed-off-by: Wyes Karny <wyes.karny@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
---
drivers/acpi/cppc_acpi.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 02d83c807271..c936ff503965 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1487,7 +1487,7 @@ EXPORT_SYMBOL_GPL(cppc_set_enable);
int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
{
struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
- struct cpc_register_resource *desired_reg;
+ 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;
int ret = 0;
@@ -1498,6 +1498,8 @@ 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];

/*
* This is Phase-I where we want to write to CPC registers
@@ -1506,7 +1508,7 @@ 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)) {
+ if (CPC_IN_PCC(desired_reg) || CPC_IN_PCC(min_perf_reg) || CPC_IN_PCC(max_perf_reg)) {
if (pcc_ss_id < 0) {
pr_debug("Invalid pcc_ss_id\n");
return -ENODEV;
@@ -1529,13 +1531,11 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
cpc_desc->write_cmd_status = 0;
}

- /*
- * Skip writing MIN/MAX until Linux knows how to come up with
- * useful values.
- */
cpc_write(cpu, desired_reg, perf_ctrls->desired_perf);
+ cpc_write(cpu, min_perf_reg, perf_ctrls->min_perf);
+ cpc_write(cpu, max_perf_reg, perf_ctrls->max_perf);

- if (CPC_IN_PCC(desired_reg))
+ if (CPC_IN_PCC(desired_reg) || CPC_IN_PCC(min_perf_reg) || CPC_IN_PCC(max_perf_reg))
up_read(&pcc_ss_data->pcc_lock); /* END Phase-I */
/*
* This is Phase-II where we transfer the ownership of PCC to Platform
@@ -1583,7 +1583,7 @@ 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)) {
+ if (CPC_IN_PCC(desired_reg) || CPC_IN_PCC(min_perf_reg) || CPC_IN_PCC(max_perf_reg)) {
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