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Message-ID: <CAJZ5v0jYfK_+CnT3jv+=jAp=r29nT2hQLb5zU48zpHZFzCRpNQ@mail.gmail.com>
Date: Wed, 7 May 2025 16:34:46 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Lifeng Zheng <zhenglifeng1@...wei.com>
Cc: rafael@...nel.org, viresh.kumar@...aro.org, pierre.gondois@....com,
sumitg@...dia.com, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
linuxarm@...wei.com, mario.limonciello@....com, yumpusamongus@...il.com,
srinivas.pandruvada@...ux.intel.com, jonathan.cameron@...wei.com,
zhanjie9@...ilicon.com, lihuisong@...wei.com, cenxinghai@...artners.com,
yubowen8@...wei.com, hepeng68@...wei.com
Subject: Re: [PATCH] cpufreq: CPPC: Support for autonomous selection in cppc_cpufreq
On Wed, May 7, 2025 at 5:19 AM Lifeng Zheng <zhenglifeng1@...wei.com> wrote:
>
> Add sysfs interfaces for CPPC autonomous selection in the cppc_cpufreq
> driver.
>
> Signed-off-by: Lifeng Zheng <zhenglifeng1@...wei.com>
> ---
> Hi Rafael,
>
> This patch is the 8th patch in [1]. After the discussion in [2], Sumit
> is OK with adding sysfs entries under cpufreq sysfs node, so I resend
> this patch. He will later send his updated patch after.
>
> Any comments appreciated!
>
> Lifeng
>
> [1] https://lore.kernel.org/all/20250206131428.3261578-1-zhenglifeng1@huawei.com/
> [2] https://lore.kernel.org/all/20250211103737.447704-1-sumitg@nvidia.com/
This is for Viresh and when all of the ACPI CPPC patches settle down.
I think that it would be better to get back to it after the 6.16 merge
window.
>
> .../ABI/testing/sysfs-devices-system-cpu | 54 +++++++++
> drivers/cpufreq/cppc_cpufreq.c | 109 ++++++++++++++++++
> 2 files changed, 163 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
> index 206079d3bd5b..37065e1b8ebc 100644
> --- a/Documentation/ABI/testing/sysfs-devices-system-cpu
> +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
> @@ -268,6 +268,60 @@ Description: Discover CPUs in the same CPU frequency coordination domain
> This file is only present if the acpi-cpufreq or the cppc-cpufreq
> drivers are in use.
>
> +What: /sys/devices/system/cpu/cpuX/cpufreq/auto_select
> +Date: May 2025
> +Contact: linux-pm@...r.kernel.org
> +Description: Autonomous selection enable
> +
> + Read/write interface to control autonomous selection enable
> + Read returns autonomous selection status:
> + 0: autonomous selection is disabled
> + 1: autonomous selection is enabled
> +
> + Write 'y' or '1' or 'on' to enable autonomous selection.
> + Write 'n' or '0' or 'off' to disable autonomous selection.
> +
> + This file is only present if the cppc-cpufreq driver is in use.
> +
> +What: /sys/devices/system/cpu/cpuX/cpufreq/auto_act_window
> +Date: May 2025
> +Contact: linux-pm@...r.kernel.org
> +Description: Autonomous activity window
> +
> + This file indicates a moving utilization sensitivity window to
> + the platform's autonomous selection policy.
> +
> + Read/write an integer represents autonomous activity window (in
> + microseconds) from/to this file. The max value to write is
> + 1270000000 but the max significand is 127. This means that if 128
> + is written to this file, 127 will be stored. If the value is
> + greater than 130, only the first two digits will be saved as
> + significand.
> +
> + Writing a zero value to this file enable the platform to
> + determine an appropriate Activity Window depending on the workload.
> +
> + Writing to this file only has meaning when Autonomous Selection is
> + enabled.
> +
> + This file is only present if the cppc-cpufreq driver is in use.
> +
> +What: /sys/devices/system/cpu/cpuX/cpufreq/energy_performance_preference_val
> +Date: May 2025
> +Contact: linux-pm@...r.kernel.org
> +Description: Energy performance preference
> +
> + Read/write an 8-bit integer from/to this file. This file
> + represents a range of values from 0 (performance preference) to
> + 0xFF (energy efficiency preference) that influences the rate of
> + performance increase/decrease and the result of the hardware's
> + energy efficiency and performance optimization policies.
> +
> + Writing to this file only has meaning when Autonomous Selection is
> + enabled.
> +
> + This file is only present if the cppc-cpufreq driver is in use.
> +
>
> What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
> Date: August 2008
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index b3d74f9adcf0..3c3d00cec298 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -808,10 +808,119 @@ static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
>
> return cpufreq_show_cpus(cpu_data->shared_cpu_map, buf);
> }
> +
> +static ssize_t show_auto_select(struct cpufreq_policy *policy, char *buf)
> +{
> + bool val;
> + int ret;
> +
> + ret = cppc_get_auto_sel(policy->cpu, &val);
> +
> + /* show "<unsupported>" when this register is not supported by cpc */
> + if (ret == -EOPNOTSUPP)
> + return sysfs_emit(buf, "<unsupported>\n");
> +
> + if (ret)
> + return ret;
> +
> + return sysfs_emit(buf, "%d\n", val);
> +}
> +
> +static ssize_t store_auto_select(struct cpufreq_policy *policy,
> + const char *buf, size_t count)
> +{
> + bool val;
> + int ret;
> +
> + ret = kstrtobool(buf, &val);
> + if (ret)
> + return ret;
> +
> + ret = cppc_set_auto_sel(policy->cpu, val);
> + if (ret)
> + return ret;
> +
> + return count;
> +}
> +
> +static ssize_t show_auto_act_window(struct cpufreq_policy *policy, char *buf)
> +{
> + u64 val;
> + int ret;
> +
> + ret = cppc_get_auto_act_window(policy->cpu, &val);
> +
> + /* show "<unsupported>" when this register is not supported by cpc */
> + if (ret == -EOPNOTSUPP)
> + return sysfs_emit(buf, "<unsupported>\n");
> +
> + if (ret)
> + return ret;
> +
> + return sysfs_emit(buf, "%llu\n", val);
> +}
> +
> +static ssize_t store_auto_act_window(struct cpufreq_policy *policy,
> + const char *buf, size_t count)
> +{
> + u64 usec;
> + int ret;
> +
> + ret = kstrtou64(buf, 0, &usec);
> + if (ret)
> + return ret;
> +
> + ret = cppc_set_auto_act_window(policy->cpu, usec);
> + if (ret)
> + return ret;
> +
> + return count;
> +}
> +
> +static ssize_t show_energy_performance_preference_val(struct cpufreq_policy *policy, char *buf)
> +{
> + u64 val;
> + int ret;
> +
> + ret = cppc_get_epp_perf(policy->cpu, &val);
> +
> + /* show "<unsupported>" when this register is not supported by cpc */
> + if (ret == -EOPNOTSUPP)
> + return sysfs_emit(buf, "<unsupported>\n");
> +
> + if (ret)
> + return ret;
> +
> + return sysfs_emit(buf, "%llu\n", val);
> +}
> +
> +static ssize_t store_energy_performance_preference_val(struct cpufreq_policy *policy,
> + const char *buf, size_t count)
> +{
> + u64 val;
> + int ret;
> +
> + ret = kstrtou64(buf, 0, &val);
> + if (ret)
> + return ret;
> +
> + ret = cppc_set_epp(policy->cpu, val);
> + if (ret)
> + return ret;
> +
> + return count;
> +}
> +
> cpufreq_freq_attr_ro(freqdomain_cpus);
> +cpufreq_freq_attr_rw(auto_select);
> +cpufreq_freq_attr_rw(auto_act_window);
> +cpufreq_freq_attr_rw(energy_performance_preference_val);
>
> static struct freq_attr *cppc_cpufreq_attr[] = {
> &freqdomain_cpus,
> + &auto_select,
> + &auto_act_window,
> + &energy_performance_preference_val,
> NULL,
> };
>
> --
> 2.33.0
>
>
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