5.15-stable review patch. If anyone has any objections, please let me know.
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From: Gautham R. Shenoy gautham.shenoy@amd.com
[ Upstream commit 0834667545962ef1c5e8684ed32b45d9c574acd3 ]
Commit 3c55e94c0ade ("cpufreq: ACPI: Extend frequency tables to cover boost frequencies") introduced an assumption in acpi_cpufreq_cpu_init() that the first entry in the P-state table was the nominal frequency. This assumption is incorrect. The frequency corresponding to the P0 P-State need not be the same as the nominal frequency advertised via CPPC.
Since the driver is using the CPPC.highest_perf and CPPC.nominal_perf to compute the boost-ratio, it makes sense to use CPPC.nominal_freq to compute the max-frequency. CPPC.nominal_freq is advertised on platforms supporting CPPC revisions 3 or higher.
Hence, fallback to using the first entry in the P-State table only on platforms that do not advertise CPPC.nominal_freq.
Fixes: 3c55e94c0ade ("cpufreq: ACPI: Extend frequency tables to cover boost frequencies") Tested-by: Dhananjay Ugwekar Dhananjay.Ugwekar@amd.com Signed-off-by: Gautham R. Shenoy gautham.shenoy@amd.com Reviewed-by: Mario Limonciello mario.limonciello@amd.com Link: https://patch.msgid.link/20250113044107.566-1-gautham.shenoy@amd.com [ rjw: Retain reverse X-mas tree ordering of local variable declarations ] [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpufreq/acpi-cpufreq.c | 36 +++++++++++++++++++++++++--------- 1 file changed, 27 insertions(+), 9 deletions(-)
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c index 28467d83c7452..4a31bd90406c9 100644 --- a/drivers/cpufreq/acpi-cpufreq.c +++ b/drivers/cpufreq/acpi-cpufreq.c @@ -630,7 +630,14 @@ static int acpi_cpufreq_blacklist(struct cpuinfo_x86 *c) #endif
#ifdef CONFIG_ACPI_CPPC_LIB -static u64 get_max_boost_ratio(unsigned int cpu) +/* + * get_max_boost_ratio: Computes the max_boost_ratio as the ratio + * between the highest_perf and the nominal_perf. + * + * Returns the max_boost_ratio for @cpu. Returns the CPPC nominal + * frequency via @nominal_freq if it is non-NULL pointer. + */ +static u64 get_max_boost_ratio(unsigned int cpu, u64 *nominal_freq) { struct cppc_perf_caps perf_caps; u64 highest_perf, nominal_perf; @@ -653,6 +660,9 @@ static u64 get_max_boost_ratio(unsigned int cpu)
nominal_perf = perf_caps.nominal_perf;
+ if (nominal_freq) + *nominal_freq = perf_caps.nominal_freq; + if (!highest_perf || !nominal_perf) { pr_debug("CPU%d: highest or nominal performance missing\n", cpu); return 0; @@ -665,8 +675,12 @@ static u64 get_max_boost_ratio(unsigned int cpu)
return div_u64(highest_perf << SCHED_CAPACITY_SHIFT, nominal_perf); } + #else -static inline u64 get_max_boost_ratio(unsigned int cpu) { return 0; } +static inline u64 get_max_boost_ratio(unsigned int cpu, u64 *nominal_freq) +{ + return 0; +} #endif
static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy) @@ -676,9 +690,9 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy) struct acpi_cpufreq_data *data; unsigned int cpu = policy->cpu; struct cpuinfo_x86 *c = &cpu_data(cpu); + u64 max_boost_ratio, nominal_freq = 0; unsigned int valid_states = 0; unsigned int result = 0; - u64 max_boost_ratio; unsigned int i; #ifdef CONFIG_SMP static int blacklisted; @@ -828,16 +842,20 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy) } freq_table[valid_states].frequency = CPUFREQ_TABLE_END;
- max_boost_ratio = get_max_boost_ratio(cpu); + max_boost_ratio = get_max_boost_ratio(cpu, &nominal_freq); if (max_boost_ratio) { - unsigned int freq = freq_table[0].frequency; + unsigned int freq = nominal_freq;
/* - * Because the loop above sorts the freq_table entries in the - * descending order, freq is the maximum frequency in the table. - * Assume that it corresponds to the CPPC nominal frequency and - * use it to set cpuinfo.max_freq. + * The loop above sorts the freq_table entries in the + * descending order. If ACPI CPPC has not advertised + * the nominal frequency (this is possible in CPPC + * revisions prior to 3), then use the first entry in + * the pstate table as a proxy for nominal frequency. */ + if (!freq) + freq = freq_table[0].frequency; + policy->cpuinfo.max_freq = freq * max_boost_ratio >> SCHED_CAPACITY_SHIFT; } else { /*