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Message-ID: <1ff97ec7-2111-e4a7-c6d5-9f1c983239e3@huawei.com>
Date: Fri, 29 May 2020 10:30:31 +0800
From: Xiongfeng Wang <wangxiongfeng2@...wei.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
CC: <viresh.kumar@...aro.org>, <Souvik.Chakravarty@....com>,
<Thanu.Rangarajan@....com>, <Sudeep.Holla@....com>,
<guohanjun@...wei.com>, <john.garry@...wei.com>,
<jonathan.cameron@...wei.com>, <linux-pm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] cpufreq: change '.set_boost' to act on only one
policy
Hi Rafael,
Thanks for your reply !
On 2020/5/28 20:48, Rafael J. Wysocki wrote:
> On Friday, May 22, 2020 5:34:35 AM CEST Xiongfeng Wang wrote:
>> Macro 'for_each_active_policy()' is defined internally. To avoid some
>> cpufreq driver needing this macro to iterate over all the policies in
>> '.set_boost' callback, we redefine '.set_boost' to act on only one
>> policy and pass the policy as an argument.
>> 'cpufreq_boost_trigger_state()' iterate over all the policies to set
>> boost for the system. This is preparation for adding SW BOOST support
>> for CPPC.
>>
>> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@...wei.com>
>> Suggested-by: Viresh Kumar <viresh.kumar@...aro.org>
>> ---
>> drivers/cpufreq/acpi-cpufreq.c | 10 ++++----
>> drivers/cpufreq/cpufreq.c | 53 +++++++++++++++++++++---------------------
>> include/linux/cpufreq.h | 2 +-
>> 3 files changed, 34 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
>> index 289e8ce..813aabf 100644
>> --- a/drivers/cpufreq/acpi-cpufreq.c
>> +++ b/drivers/cpufreq/acpi-cpufreq.c
>> @@ -126,12 +126,14 @@ static void boost_set_msr_each(void *p_en)
>> boost_set_msr(enable);
>> }
>>
>> -static int set_boost(int val)
>> +static int set_boost(struct cpufreq_policy *policy, int val)
>> {
>> get_online_cpus();
>> - on_each_cpu(boost_set_msr_each, (void *)(long)val, 1);
>> + on_each_cpu_mask(policy->cpus, boost_set_msr_each,
>> + (void *)(long)val, 1);
>> put_online_cpus();
>> - pr_debug("Core Boosting %sabled.\n", val ? "en" : "dis");
>> + pr_debug("CPU %*pbl: Core Boosting %sabled.\n",
>> + cpumask_pr_args(policy->cpus), val ? "en" : "dis");
>>
>> return 0;
>> }
>> @@ -162,7 +164,7 @@ static ssize_t store_cpb(struct cpufreq_policy *policy, const char *buf,
>> if (ret || val > 1)
>> return -EINVAL;
>>
>> - set_boost(val);
>> + set_boost(policy, val);
>>
>> return count;
>> }
>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>> index d03f250..d0d86b1 100644
>> --- a/drivers/cpufreq/cpufreq.c
>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -2532,34 +2532,29 @@ void cpufreq_update_limits(unsigned int cpu)
>> /*********************************************************************
>> * BOOST *
>> *********************************************************************/
>> -static int cpufreq_boost_set_sw(int state)
>> +static int cpufreq_boost_set_sw(struct cpufreq_policy *policy, int state)
>> {
>> - struct cpufreq_policy *policy;
>> -
>> - for_each_active_policy(policy) {
>> - int ret;
>> -
>> - if (!policy->freq_table)
>> - return -ENXIO;
>> + int ret;
>>
>> - ret = cpufreq_frequency_table_cpuinfo(policy,
>> - policy->freq_table);
>> - if (ret) {
>> - pr_err("%s: Policy frequency update failed\n",
>> - __func__);
>> - return ret;
>> - }
>> + if (!policy->freq_table)
>> + return -ENXIO;
>>
>> - ret = freq_qos_update_request(policy->max_freq_req, policy->max);
>> - if (ret < 0)
>> - return ret;
>> + ret = cpufreq_frequency_table_cpuinfo(policy, policy->freq_table);
>> + if (ret) {
>> + pr_err("%s: Policy frequency update failed\n", __func__);
>> + return ret;
>> }
>>
>> + ret = freq_qos_update_request(policy->max_freq_req, policy->max);
>> + if (ret < 0)
>> + return ret;
>> +
>> return 0;
>> }
>>
>> int cpufreq_boost_trigger_state(int state)
>> {
>> + struct cpufreq_policy *policy;
>> unsigned long flags;
>> int ret = 0;
>>
>> @@ -2570,16 +2565,22 @@ int cpufreq_boost_trigger_state(int state)
>
> AFAICS this gets called via sysfs without any cpufreq locking whatever, so
> I'm not really sure what causes it to be safe with respect to CPU offline /
> online, especially if the ->set_boost() callback only wants to do stuff
> for CPUs that are online.
Thanks for your advice. Yes, we have 'cpu_hotplug_lock' in 'set_boost' in
acpi_cpufreq. But we don't have 'cpu_hotplug_lock' for the general SW BOOST
framework. So I think I will need to move the lock from 'set_boost()' to
'store_cpb()' and add lock in 'cpufreq_boost_trigger_state' for the general SW
BOOST.
Thanks,
Xiongfeng
>
>> cpufreq_driver->boost_enabled = state;
>> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>>
>> - ret = cpufreq_driver->set_boost(state);
>> - if (ret) {
>> - write_lock_irqsave(&cpufreq_driver_lock, flags);
>> - cpufreq_driver->boost_enabled = !state;
>> - write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>> -
>> - pr_err("%s: Cannot %s BOOST\n",
>> - __func__, state ? "enable" : "disable");
>> + for_each_active_policy(policy) {
>> + ret = cpufreq_driver->set_boost(policy, state);
>> + if (ret)
>> + goto err_reset_state;
>> }
>>
>> + return 0;
>> +
>> +err_reset_state:
>> + write_lock_irqsave(&cpufreq_driver_lock, flags);
>> + cpufreq_driver->boost_enabled = !state;
>> + write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>> +
>> + pr_err("%s: Cannot %s BOOST\n",
>> + __func__, state ? "enable" : "disable");
>> +
>> return ret;
>> }
>>
>> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
>> index 67d5950..3494f67 100644
>> --- a/include/linux/cpufreq.h
>> +++ b/include/linux/cpufreq.h
>> @@ -367,7 +367,7 @@ struct cpufreq_driver {
>>
>> /* platform specific boost support code */
>> bool boost_enabled;
>> - int (*set_boost)(int state);
>> + int (*set_boost)(struct cpufreq_policy *policy, int state);
>> };
>>
>> /* flags */
>>
>
>
>
>
>
> .
>
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