Re: [PATCH V4 2/4] cpufreq: intel_pstate: Migrate to ->offline() instead of ->stop_cpu()
From: Rafael J. Wysocki <hidden>
Date: 2021-06-23 15:13:06
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On Wednesday, June 23, 2021 6:24:40 AM CEST Viresh Kumar wrote:
quoted hunk ↗ jump to hunk
commit 367dc4aa932b ("cpufreq: Add stop CPU callback to cpufreq_driver interface") added the stop_cpu() callback to allow the drivers to do clean up before the CPU is completely down and its state can't be modified. At that time the CPU hotplug framework used to call the cpufreq core's registered notifier for different events like CPU_DOWN_PREPARE and CPU_POST_DEAD. The stop_cpu() callback was called during the CPU_DOWN_PREPARE event. This is no longer the case, cpuhp_cpufreq_offline() is called only once by the CPU hotplug core now and we don't really need to separately call stop_cpu() for cpufreq drivers. Migrate to using the offline() callbacks instead of stop_cpu(). Cc: Dirk Brandewie <redacted> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/intel_pstate.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 0e69dffd5a76..b4c0ff7f5b71 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c@@ -2335,6 +2335,8 @@ static int intel_pstate_cpu_offline(struct cpufreq_policy *policy) pr_debug("CPU %d going offline\n", cpu->cpu); + intel_pstate_clear_update_util_hook(policy->cpu);
As mentioned already in https://lore.kernel.org/linux-pm/CAJZ5v0g2tCZptcqh+c55YYiO7rDHmZivMLsmpq_7005zNPN1xg@mail.gmail.com/ (local) this isn't particularly clean, because intel_pstate_cpu_offline() is also used in the passive mode where the above call is not needed. I would make a change like in the patch below instead.
+ if (cpu->suspended) return 0;
--- From: Rafael J. Wysocki <redacted> Subject: [PATCH] cpufreq: intel_pstate: Combine ->stop_cpu() and ->offline() Combine the ->stop_cpu() and ->offline() callback routines for the active mode of intel_pstate so as to avoid setting the ->stop_cpu callback pointer which is going to be dropped from the framework. Signed-off-by: Rafael J. Wysocki <redacted> --- drivers/cpufreq/intel_pstate.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) Index: linux-pm/drivers/cpufreq/intel_pstate.c ===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c@@ -2577,11 +2577,13 @@ static int intel_pstate_cpu_online(struc return 0; } -static void intel_pstate_stop_cpu(struct cpufreq_policy *policy) +static int intel_pstate_stop_cpu(struct cpufreq_policy *policy) { pr_debug("CPU %d stopping\n", policy->cpu); intel_pstate_clear_update_util_hook(policy->cpu); + + return intel_pstate_cpu_offline(policy); } static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
@@ -2654,8 +2656,7 @@ static struct cpufreq_driver intel_pstat .resume = intel_pstate_resume, .init = intel_pstate_cpu_init, .exit = intel_pstate_cpu_exit, - .stop_cpu = intel_pstate_stop_cpu, - .offline = intel_pstate_cpu_offline, + .offline = intel_pstate_stop_cpu, .online = intel_pstate_cpu_online, .update_limits = intel_pstate_update_limits, .name = "intel_pstate",