From: Viresh Kumar <viresh.kumar@linaro.org>
To: Rafael Wysocki <rjw@rjwysocki.net>,
Ionela Voinescu <ionela.voinescu@arm.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Jonathan Corbet <corbet@lwn.net>
Cc: linux-pm@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
Qian Cai <quic_qiancai@quicinc.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH V2 1/3] cpufreq: Add start_cpu() and stop_cpu() callbacks
Date: Wed, 16 Jun 2021 12:18:07 +0530 [thread overview]
Message-ID: <2ffbaf079a21c2810c402cb5bba4e9c14c4a0ff4.1623825725.git.viresh.kumar@linaro.org> (raw)
In-Reply-To: <cover.1623825725.git.viresh.kumar@linaro.org>
On CPU hot-unplug, the cpufreq core doesn't call any driver specific
callback unless all the CPUs of a policy went away, in which case we
call stop_cpu() callback.
For the CPPC cpufreq driver, we need to perform per-cpu init/exit work
which that can't be performed from policy specific init()/exit()
callbacks.
This patch adds a new callback, start_cpu() and modifies the stop_cpu()
callback, to perform such CPU specific work.
These routines are called whenever a CPU is added or removed from a
policy.
Note that this also moves the setting of policy->cpus to online CPUs
only, outside of rwsem as we needed to call start_cpu() for online CPUs
only. This shouldn't have any side effects.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
Documentation/cpu-freq/cpu-drivers.rst | 7 +++++--
drivers/cpufreq/cpufreq.c | 19 +++++++++++++++----
include/linux/cpufreq.h | 5 ++++-
3 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/Documentation/cpu-freq/cpu-drivers.rst b/Documentation/cpu-freq/cpu-drivers.rst
index a697278ce190..15cfe42b4075 100644
--- a/Documentation/cpu-freq/cpu-drivers.rst
+++ b/Documentation/cpu-freq/cpu-drivers.rst
@@ -71,8 +71,11 @@ And optionally
.exit - A pointer to a per-policy cleanup function called during
CPU_POST_DEAD phase of cpu hotplug process.
- .stop_cpu - A pointer to a per-policy stop function called during
- CPU_DOWN_PREPARE phase of cpu hotplug process.
+ .start_cpu - A pointer to a per-policy per-cpu start function called
+ during CPU online phase.
+
+ .stop_cpu - A pointer to a per-policy per-cpu stop function called
+ during CPU offline phase.
.suspend - A pointer to a per-policy suspend function which is called
with interrupts disabled and _after_ the governor is stopped for the
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 802abc925b2a..128dfb1b0cdf 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1119,6 +1119,10 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp
cpumask_set_cpu(cpu, policy->cpus);
+ /* Do CPU specific initialization if required */
+ if (cpufreq_driver->start_cpu)
+ cpufreq_driver->start_cpu(policy, cpu);
+
if (has_target()) {
ret = cpufreq_start_governor(policy);
if (ret)
@@ -1375,13 +1379,19 @@ static int cpufreq_online(unsigned int cpu)
cpumask_copy(policy->related_cpus, policy->cpus);
}
- down_write(&policy->rwsem);
/*
* affected cpus must always be the one, which are online. We aren't
* managing offline cpus here.
*/
cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
+ /* Do CPU specific initialization if required */
+ if (cpufreq_driver->start_cpu) {
+ for_each_cpu(j, policy->cpus)
+ cpufreq_driver->start_cpu(policy, j);
+ }
+
+ down_write(&policy->rwsem);
if (new_policy) {
for_each_cpu(j, policy->related_cpus) {
per_cpu(cpufreq_cpu_data, j) = policy;
@@ -1581,6 +1591,10 @@ static int cpufreq_offline(unsigned int cpu)
policy->cpu = cpumask_any(policy->cpus);
}
+ /* Do CPU specific de-initialization if required */
+ if (cpufreq_driver->stop_cpu)
+ cpufreq_driver->stop_cpu(policy, cpu);
+
/* Start governor again for active policy */
if (!policy_is_inactive(policy)) {
if (has_target()) {
@@ -1597,9 +1611,6 @@ static int cpufreq_offline(unsigned int cpu)
policy->cdev = NULL;
}
- if (cpufreq_driver->stop_cpu)
- cpufreq_driver->stop_cpu(policy);
-
if (has_target())
cpufreq_exit_governor(policy);
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 353969c7acd3..c281b3df4e2f 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -371,7 +371,10 @@ struct cpufreq_driver {
int (*online)(struct cpufreq_policy *policy);
int (*offline)(struct cpufreq_policy *policy);
int (*exit)(struct cpufreq_policy *policy);
- void (*stop_cpu)(struct cpufreq_policy *policy);
+
+ /* CPU specific start/stop */
+ void (*start_cpu)(struct cpufreq_policy *policy, unsigned int cpu);
+ void (*stop_cpu)(struct cpufreq_policy *policy, unsigned int cpu);
int (*suspend)(struct cpufreq_policy *policy);
int (*resume)(struct cpufreq_policy *policy);
--
2.31.1.272.g89b43f80a514
next prev parent reply other threads:[~2021-06-16 6:48 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 6:48 [PATCH V2 0/3] cpufreq: cppc: Add support for frequency invariance Viresh Kumar
2021-06-16 6:48 ` Viresh Kumar [this message]
2021-06-17 13:33 ` [PATCH V2 1/3] cpufreq: Add start_cpu() and stop_cpu() callbacks Rafael J. Wysocki
2021-06-18 7:46 ` Viresh Kumar
2021-06-16 6:48 ` [PATCH V2 2/3] arch_topology: Avoid use-after-free for scale_freq_data Viresh Kumar
2021-06-16 7:57 ` Greg Kroah-Hartman
2021-06-16 8:18 ` Viresh Kumar
2021-06-16 8:31 ` Greg Kroah-Hartman
2021-06-16 9:10 ` Viresh Kumar
2021-06-16 11:25 ` Ionela Voinescu
2021-06-16 11:36 ` Viresh Kumar
2021-06-16 12:00 ` Ionela Voinescu
2021-06-17 3:06 ` Viresh Kumar
2021-06-16 6:48 ` [PATCH V2 3/3] cpufreq: CPPC: Add support for frequency invariance Viresh Kumar
2021-06-16 12:48 ` Ionela Voinescu
2021-06-17 3:24 ` Viresh Kumar
2021-06-17 10:34 ` Ionela Voinescu
2021-06-17 11:19 ` Viresh Kumar
2021-06-17 12:22 ` Peter Zijlstra
2021-06-18 3:45 ` Viresh Kumar
2021-06-18 7:37 ` Viresh Kumar
2021-06-18 12:26 ` Ionela Voinescu
2021-06-16 10:02 ` [PATCH V2 0/3] cpufreq: cppc: " Vincent Guittot
2021-06-16 11:54 ` Viresh Kumar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2ffbaf079a21c2810c402cb5bba4e9c14c4a0ff4.1623825725.git.viresh.kumar@linaro.org \
--to=viresh.kumar@linaro.org \
--cc=corbet@lwn.net \
--cc=ionela.voinescu@arm.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=quic_qiancai@quicinc.com \
--cc=rjw@rjwysocki.net \
--cc=vincent.guittot@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).