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ACPI: CPPC: Do not use CPUFREQ_ETERNAL as an error value 

Instead of using CPUFREQ_ETERNAL for signaling an error condition
in cppc_get_transition_latency(), change the return value type of
that function to int and make it return a proper negative error
code on failures.

No intentional functional impact.

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Jie Zhan <zhanjie9@hisilicon.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Qais Yousef <qyousef@layalina.io>
pull/1354/merge
Rafael J. Wysocki 2025-09-26 12:29:50 +02:00
parent f965d111e6
commit c28a280bd4
4 changed files with 16 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/acpi/cppc_acpi.c
View File

@ -1876,7 +1876,7 @@ EXPORT_SYMBOL_GPL(cppc_set_perf);
* If desired_reg is in the SystemMemory or SystemIo ACPI address space, * If desired_reg is in the SystemMemory or SystemIo ACPI address space,
* then assume there is no latency. * then assume there is no latency.
*/ */
unsigned int cppc_get_transition_latency(int cpu_num) int cppc_get_transition_latency(int cpu_num)
{ {
/* /*
* Expected transition latency is based on the PCCT timing values * Expected transition latency is based on the PCCT timing values
@ -1889,31 +1889,29 @@ unsigned int cppc_get_transition_latency(int cpu_num)
* completion of a command before issuing the next command, * completion of a command before issuing the next command,
* in microseconds. * in microseconds.
*/ */
unsigned int latency_ns = 0;
struct cpc_desc *cpc_desc; struct cpc_desc *cpc_desc;
struct cpc_register_resource *desired_reg; struct cpc_register_resource *desired_reg;
int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu_num); int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu_num);
struct cppc_pcc_data *pcc_ss_data; struct cppc_pcc_data *pcc_ss_data;
int latency_ns = 0;
cpc_desc = per_cpu(cpc_desc_ptr, cpu_num); cpc_desc = per_cpu(cpc_desc_ptr, cpu_num);
if (!cpc_desc) if (!cpc_desc)
return CPUFREQ_ETERNAL; return -ENODATA;
desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF]; desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
if (CPC_IN_SYSTEM_MEMORY(desired_reg) || CPC_IN_SYSTEM_IO(desired_reg)) if (CPC_IN_SYSTEM_MEMORY(desired_reg) || CPC_IN_SYSTEM_IO(desired_reg))
return 0; return 0;
else if (!CPC_IN_PCC(desired_reg))
return CPUFREQ_ETERNAL;
if (pcc_ss_id < 0) if (!CPC_IN_PCC(desired_reg) || pcc_ss_id < 0)
return CPUFREQ_ETERNAL; return -ENODATA;
pcc_ss_data = pcc_data[pcc_ss_id]; pcc_ss_data = pcc_data[pcc_ss_id];
if (pcc_ss_data->pcc_mpar) if (pcc_ss_data->pcc_mpar)
latency_ns = 60 * (1000 * 1000 * 1000 / pcc_ss_data->pcc_mpar); latency_ns = 60 * (1000 * 1000 * 1000 / pcc_ss_data->pcc_mpar);
latency_ns = max(latency_ns, pcc_ss_data->pcc_nominal * 1000); latency_ns = max_t(int, latency_ns, pcc_ss_data->pcc_nominal * 1000);
latency_ns = max(latency_ns, pcc_ss_data->pcc_mrtt * 1000); latency_ns = max_t(int, latency_ns, pcc_ss_data->pcc_mrtt * 1000);
return latency_ns; return latency_ns;
} }

8
drivers/cpufreq/amd-pstate.c
View File

@ -872,10 +872,10 @@ static void amd_pstate_update_limits(struct cpufreq_policy *policy)
*/ */
static u32 amd_pstate_get_transition_delay_us(unsigned int cpu) static u32 amd_pstate_get_transition_delay_us(unsigned int cpu)
{ {
u32 transition_delay_ns; int transition_delay_ns;
transition_delay_ns = cppc_get_transition_latency(cpu); transition_delay_ns = cppc_get_transition_latency(cpu);
if (transition_delay_ns == CPUFREQ_ETERNAL) { if (transition_delay_ns < 0) {
if (cpu_feature_enabled(X86_FEATURE_AMD_FAST_CPPC)) if (cpu_feature_enabled(X86_FEATURE_AMD_FAST_CPPC))
return AMD_PSTATE_FAST_CPPC_TRANSITION_DELAY; return AMD_PSTATE_FAST_CPPC_TRANSITION_DELAY;
else else
@ -891,10 +891,10 @@ static u32 amd_pstate_get_transition_delay_us(unsigned int cpu)
*/ */
static u32 amd_pstate_get_transition_latency(unsigned int cpu) static u32 amd_pstate_get_transition_latency(unsigned int cpu)
{ {
u32 transition_latency; int transition_latency;
transition_latency = cppc_get_transition_latency(cpu); transition_latency = cppc_get_transition_latency(cpu);
if (transition_latency == CPUFREQ_ETERNAL) if (transition_latency < 0)
return AMD_PSTATE_TRANSITION_LATENCY; return AMD_PSTATE_TRANSITION_LATENCY;
return transition_latency; return transition_latency;

4
drivers/cpufreq/cppc_cpufreq.c
View File

@ -310,9 +310,9 @@ static int cppc_verify_policy(struct cpufreq_policy_data *policy)
static unsigned int __cppc_cpufreq_get_transition_delay_us(unsigned int cpu) static unsigned int __cppc_cpufreq_get_transition_delay_us(unsigned int cpu)
{ {
unsigned int transition_latency_ns = cppc_get_transition_latency(cpu); int transition_latency_ns = cppc_get_transition_latency(cpu);
if (transition_latency_ns == CPUFREQ_ETERNAL) if (transition_latency_ns < 0)
return CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS / NSEC_PER_USEC; return CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS / NSEC_PER_USEC;
return transition_latency_ns / NSEC_PER_USEC; return transition_latency_ns / NSEC_PER_USEC;

6
include/acpi/cppc_acpi.h
View File

@ -160,7 +160,7 @@ extern unsigned int cppc_khz_to_perf(struct cppc_perf_caps *caps, unsigned int f
extern bool acpi_cpc_valid(void); extern bool acpi_cpc_valid(void);
extern bool cppc_allow_fast_switch(void); extern bool cppc_allow_fast_switch(void);
extern int acpi_get_psd_map(unsigned int cpu, struct cppc_cpudata *cpu_data); extern int acpi_get_psd_map(unsigned int cpu, struct cppc_cpudata *cpu_data);
extern unsigned int cppc_get_transition_latency(int cpu); extern int cppc_get_transition_latency(int cpu);
extern bool cpc_ffh_supported(void); extern bool cpc_ffh_supported(void);
extern bool cpc_supported_by_cpu(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(int cpunum, struct cpc_reg *reg, u64 *val);
@ -216,9 +216,9 @@ static inline bool cppc_allow_fast_switch(void)
{ {
return false; return false;
} }
static inline unsigned int cppc_get_transition_latency(int cpu) static inline int cppc_get_transition_latency(int cpu)
{ {
return CPUFREQ_ETERNAL; return -ENODATA;
} }
static inline bool cpc_ffh_supported(void) static inline bool cpc_ffh_supported(void)
{ {