Re: [PATCH v13 3/9] cpufreq: introduce init_boost callback to initialize boost state for pstate drivers

From: Mario Limonciello
Date: Mon Jun 24 2024 - 17:48:15 EST


On 6/21/2024 11:50, Perry Yuan wrote:
Introduce a new init_boost callback in cpufreq to initialize the boost
state for specific pstate drivers. This initialization is required before
calling the set_boost interface for each CPU.

The init_boost callback will set up and synchronize each CPU's current
boost state before invoking the set_boost function. Without this step,
the boost state may be inconsistent across CPUs.

Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>

As a part of the testing on the v13 series the past few days, we realized that this patch is not necessary. It's really a workaround for a change in behavior introduced in

f37a4d6b4a2c ("cpufreq: Fix per-policy boost behavior on SoCs using cpufreq_boost_set_sw()")

I've adjusted the series (as v14) to drop this patch and instead send a fix for that one.

---
drivers/cpufreq/cpufreq.c | 14 ++++++++++++--
include/linux/cpufreq.h | 2 ++
2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1fdabb660231..0c99d2dfdb53 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1429,8 +1429,18 @@ static int cpufreq_online(unsigned int cpu)
goto out_free_policy;
}
- /* Let the per-policy boost flag mirror the cpufreq_driver boost during init */
- policy->boost_enabled = cpufreq_boost_enabled() && policy_has_boost_freq(policy);
+ /* init boost state to prepare set_boost callback for each CPU */
+ if (cpufreq_driver->init_boost) {
+ ret = cpufreq_driver->init_boost(policy);
+ if (ret) {
+ pr_debug("%s: %d: boost initialization failed\n", __func__,
+ __LINE__);
+ goto out_offline_policy;
+ }
+ } else {
+ /* Let the per-policy boost flag mirror the cpufreq_driver boost during init */
+ policy->boost_enabled = cpufreq_boost_enabled() && policy_has_boost_freq(policy);
+ }
/*
* The initialization has succeeded and the policy is online.
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 20f7e98ee8af..0698c0292d8f 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -409,6 +409,8 @@ struct cpufreq_driver {
bool boost_enabled;
int (*set_boost)(struct cpufreq_policy *policy, int state);
+ /* initialize boost state to be consistent before calling set_boost */
+ int (*init_boost)(struct cpufreq_policy *policy);
/*
* Set by drivers that want to register with the energy model after the
* policy is properly initialized, but before the governor is started.