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>

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 6b649031808f805b2bf4212d2ffca6719013d098..ab4651205e8adbcb027ec3bd206d676f0fc6122a 100644 (file)
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1876,7 +1876,7 @@ EXPORT_SYMBOL_GPL(cppc_set_perf);
  * If desired_reg is in the SystemMemory or SystemIo ACPI address space,
  * 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
@@ -1889,31 +1889,29 @@ unsigned int cppc_get_transition_latency(int cpu_num)
         *              completion of a command before issuing the next command,
         *              in microseconds.
         */
-       unsigned int latency_ns = 0;
        struct cpc_desc *cpc_desc;
        struct cpc_register_resource *desired_reg;
        int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu_num);
        struct cppc_pcc_data *pcc_ss_data;
+       int latency_ns = 0;
 
        cpc_desc = per_cpu(cpc_desc_ptr, cpu_num);
        if (!cpc_desc)
-               return CPUFREQ_ETERNAL;
+               return -ENODATA;
 
        desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
        if (CPC_IN_SYSTEM_MEMORY(desired_reg) || CPC_IN_SYSTEM_IO(desired_reg))
                return 0;
-       else if (!CPC_IN_PCC(desired_reg))
-               return CPUFREQ_ETERNAL;
 
-       if (pcc_ss_id < 0)
-               return CPUFREQ_ETERNAL;
+       if (!CPC_IN_PCC(desired_reg) || pcc_ss_id < 0)
+               return -ENODATA;
 
        pcc_ss_data = pcc_data[pcc_ss_id];
        if (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(latency_ns, pcc_ss_data->pcc_mrtt * 1000);
+       latency_ns = max_t(int, latency_ns, pcc_ss_data->pcc_nominal * 1000);
+       latency_ns = max_t(int, latency_ns, pcc_ss_data->pcc_mrtt * 1000);
 
        return latency_ns;
 }

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index b4c79fde1979b6a73dc4b06a740247e1218e1db5..298e92d8cc0315dfbfdbae74097cc590bae3b89c 100644 (file)
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -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)
 {
-       u32 transition_delay_ns;
+       int transition_delay_ns;
 
        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))
                        return AMD_PSTATE_FAST_CPPC_TRANSITION_DELAY;
                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)
 {
-       u32 transition_latency;
+       int transition_latency;
 
        transition_latency = cppc_get_transition_latency(cpu);
-       if (transition_latency  == CPUFREQ_ETERNAL)
+       if (transition_latency < 0)
                return AMD_PSTATE_TRANSITION_LATENCY;
 
        return transition_latency;

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index b71946937c52632aa650f00f3d1dfc82eed366f3..e23d9abea13592d8818157bd79286cfd6db2f896 100644 (file)
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -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)
 {
-       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 transition_latency_ns / NSEC_PER_USEC;

diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
index 20f3d62e7a16a33d27ab18c2431dab9283699fde..13fa81504844563f84bf8b75efed7915b662acfe 100644 (file)
--- a/include/acpi/cppc_acpi.h
+++ b/include/acpi/cppc_acpi.h
@@ -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 cppc_allow_fast_switch(void);
 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_supported_by_cpu(void);
 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;
 }
-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)
 {