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ACPI: CPPC: Introduce cppc_get_nominal_perf()

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On some systems the nominal_perf value retrieved via CPPC is just
a constant and fetching it doesn't require accessing any registers,
so if it is the only CPPC capability that's needed, it is wasteful
to run cppc_get_perf_caps() in order to get just that value alone,
especially when this is done for CPUs other than the one running
the code.

For this reason, introduce cppc_get_nominal_perf() allowing
nominal_perf to be obtained individually, by generalizing the
existing cppc_get_desired_perf() (and renaming it) so it can be
used to retrieve any specific CPPC capability value.

While at it, clean up the cppc_get_desired_perf() kerneldoc comment
a bit.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2021-09-04 15:51:45 +02:00
parent 27de8d5970
commit 0654cf05d1
2 changed files with 36 additions and 16 deletions
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45
drivers/acpi/cppc_acpi.c
View File

@ -1008,23 +1008,14 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
return ret_val;
}
/**
* cppc_get_desired_perf - Get the value of desired performance register.
* @cpunum: CPU from which to get desired performance.
* @desired_perf: address of a variable to store the returned desired performance
*
* Return: 0 for success, -EIO otherwise.
*/
int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
{
struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
struct cpc_register_resource *reg = &cpc_desc->cpc_regs[reg_idx];
if (CPC_IN_PCC(reg)) {
int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
struct cpc_register_resource *desired_reg;
struct cppc_pcc_data *pcc_ss_data = NULL;
desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
if (CPC_IN_PCC(desired_reg)) {
int ret = 0;
if (pcc_ss_id < 0)
@ -1035,7 +1026,7 @@ int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
down_write(&pcc_ss_data->pcc_lock);
if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
cpc_read(cpunum, desired_reg, desired_perf);
cpc_read(cpunum, reg, perf);
else
ret = -EIO;
@ -1044,12 +1035,36 @@ int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
return ret;
}
cpc_read(cpunum, desired_reg, desired_perf);
cpc_read(cpunum, reg, perf);
return 0;
}
/**
* cppc_get_desired_perf - Get the desired performance register value.
* @cpunum: CPU from which to get desired performance.
* @desired_perf: Return address.
*
* Return: 0 for success, -EIO otherwise.
*/
int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
{
return cppc_get_perf(cpunum, DESIRED_PERF, desired_perf);
}
EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
/**
* cppc_get_nominal_perf - Get the nominal performance register value.
* @cpunum: CPU from which to get nominal performance.
* @nominal_perf: Return address.
*
* Return: 0 for success, -EIO otherwise.
*/
int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
{
return cppc_get_perf(cpunum, NOMINAL_PERF, nominal_perf);
}
/**
* cppc_get_perf_caps - Get a CPU's performance capabilities.
* @cpunum: CPU from which to get capabilities info.

5
include/acpi/cppc_acpi.h
View File

@ -135,6 +135,7 @@ struct cppc_cpudata {
#ifdef CONFIG_ACPI_CPPC_LIB
extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf);
extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
@ -149,6 +150,10 @@ static inline int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
{
return -ENOTSUPP;
}
static inline int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
{
return -ENOTSUPP;
}
static inline int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
{
return -ENOTSUPP;