From 069a2bb8c48c43176f2f0e6cae5efe2f39f6bdf2 Mon Sep 17 00:00:00 2001 From: Perry Yuan Date: Thu, 25 Apr 2024 16:07:56 +0800 Subject: [PATCH] cpufreq: amd-pstate: get transition delay and latency value from ACPI tables Make pstate driver initially retrieve the P-state transition delay and latency values from the BIOS ACPI tables which has more reasonable delay and latency values according to the platform design and requirements. Previously there values were hardcoded at specific value which may have conflicted with platform and it might not reflect the most accurate or optimized setting for the processor. [054h 0084 8] Preserve Mask : FFFFFFFF00000000 [05Ch 0092 8] Write Mask : 0000000000000001 [064h 0100 4] Command Latency : 00000FA0 [068h 0104 4] Maximum Access Rate : 0000EA60 [06Ch 0108 2] Minimum Turnaround Time : 0000 Reviewed-by: Gautham R. Shenoy Reviewed-by: Mario Limonciello Tested-by: Dhananjay Ugwekar Signed-off-by: Perry Yuan Acked-by: Huang Rui Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/amd-pstate.c | 34 ++++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 960fead0b83e2..510b5aec42ea0 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -756,6 +756,36 @@ free_cpufreq_put: mutex_unlock(&amd_pstate_driver_lock); } +/** + * Get pstate transition delay time from ACPI tables that firmware set + * instead of using hardcode value directly. + */ +static u32 amd_pstate_get_transition_delay_us(unsigned int cpu) +{ + u32 transition_delay_ns; + + transition_delay_ns = cppc_get_transition_latency(cpu); + if (transition_delay_ns == CPUFREQ_ETERNAL) + return AMD_PSTATE_TRANSITION_DELAY; + + return transition_delay_ns / NSEC_PER_USEC; +} + +/** + * Get pstate transition latency value from ACPI tables that firmware + * set instead of using hardcode value directly. + */ +static u32 amd_pstate_get_transition_latency(unsigned int cpu) +{ + u32 transition_latency; + + transition_latency = cppc_get_transition_latency(cpu); + if (transition_latency == CPUFREQ_ETERNAL) + return AMD_PSTATE_TRANSITION_LATENCY; + + return transition_latency; +} + /** * amd_pstate_init_freq: Initialize the max_freq, min_freq, * nominal_freq and lowest_nonlinear_freq for @@ -848,8 +878,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy) goto free_cpudata1; } - policy->cpuinfo.transition_latency = AMD_PSTATE_TRANSITION_LATENCY; - policy->transition_delay_us = AMD_PSTATE_TRANSITION_DELAY; + policy->cpuinfo.transition_latency = amd_pstate_get_transition_latency(policy->cpu); + policy->transition_delay_us = amd_pstate_get_transition_delay_us(policy->cpu); policy->min = min_freq; policy->max = max_freq; -- 2.30.2