github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-22 12:44:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

ACPI: CPPC: add paired FFH feedback-counter read hook

Browse Source 
cppc_get_perf_ctrs() reads the delivered and reference performance
counters one at a time.

Allow architectures to provide both FFH feedback counters in one
operation when that either narrows the sampling window or avoids extra
cross-CPU reads. Add a small FFH-specific hook for that case and fall
back to the existing per-register reads when unsupported.

Tested-by: Sumit Gupta <sumitg@nvidia.com>
Reviewed-by: Sumit Gupta <sumitg@nvidia.com>
Tested-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Reviewed-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Signed-off-by: Pengjie Zhang <zhangpengjie2@huawei.com>
Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Pengjie Zhang 2026-07-08 16:28:17 +08:00 committed by Will Deacon
parent a13c140cc2
commit 9aa7df5205
2 changed files with 52 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
drivers/acpi/cppc_acpi.c
View File

@ -1004,6 +1004,22 @@ int __weak cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
return -ENOTSUPP;
}
/**
* cpc_read_ffh_fb_ctrs() - Read FFH feedback counters together
* @cpunum: Target CPU
* @reg1: first CPPC register information
* @val1: place holder for first return value
* @reg2: second CPPC register information
* @val2: place holder for second return value
*
* Return: 0 on success, error code otherwise
*/
int __weak cpc_read_ffh_fb_ctrs(int cpunum, struct cpc_reg *reg1,
u64 *val1, struct cpc_reg *reg2, u64 *val2)
{
return -EOPNOTSUPP;
}
/**
* cpc_write_ffh() - Write FFH register
* @cpunum: CPU number to write
@ -1496,6 +1512,33 @@ bool cppc_perf_ctrs_in_pcc_cpu(unsigned int cpu)
}
EXPORT_SYMBOL_GPL(cppc_perf_ctrs_in_pcc_cpu);
static int cppc_read_fb_ctrs(int cpunum,
struct cpc_register_resource *delivered_reg,
struct cpc_register_resource *reference_reg,
u64 *delivered, u64 *reference)
{
int ret;
/*
* For FFH feedback counters, try a paired read first to reduce
* sampling skew between delivered and reference counters. Fall
* back to the existing per-register reads if unsupported.
*/
if (CPC_IN_FFH(delivered_reg) && CPC_IN_FFH(reference_reg)) {
ret = cpc_read_ffh_fb_ctrs(cpunum,
&delivered_reg->cpc_entry.reg, delivered,
&reference_reg->cpc_entry.reg, reference);
if (ret != -EOPNOTSUPP)
return ret;
}
ret = cpc_read(cpunum, delivered_reg, delivered);
if (ret)
return ret;
return cpc_read(cpunum, reference_reg, reference);
}
/**
* cppc_perf_ctrs_in_pcc - Check if any perf counters are in a PCC region.
*
@ -1561,11 +1604,8 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
}
}
ret = cpc_read(cpunum, delivered_reg, &delivered);
if (ret)
goto out_err;
ret = cpc_read(cpunum, reference_reg, &reference);
ret = cppc_read_fb_ctrs(cpunum, delivered_reg, reference_reg,
&delivered, &reference);
if (ret)
goto out_err;

7
include/acpi/cppc_acpi.h
View File

@ -176,6 +176,8 @@ extern int cppc_get_transition_latency(int cpu);
extern bool cpc_ffh_supported(void);
extern bool cpc_supported_by_cpu(void);
extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val);
extern int cpc_read_ffh_fb_ctrs(int cpu, struct cpc_reg *reg1, u64 *val1,
struct cpc_reg *reg2, u64 *val2);
extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val);
extern int cppc_get_epp_perf(int cpunum, u64 *epp_perf);
extern int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable);
@ -250,6 +252,11 @@ static inline int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
{
return -EOPNOTSUPP;
}
static inline int cpc_read_ffh_fb_ctrs(int cpu, struct cpc_reg *reg1, u64 *val1,
struct cpc_reg *reg2, u64 *val2)
{
return -EOPNOTSUPP;
}
static inline int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
{
return -EOPNOTSUPP;