linux-kernel - Re: [PATCH v5 0/8] Support for autonomous selection in cppc

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Message-ID: <828ab846-fe03-4830-a722-a86e57ba89c7@arm.com>
Date: Mon, 24 Feb 2025 11:31:29 +0100
From: Pierre Gondois <pierre.gondois@....com>
To: "zhenglifeng (A)" <zhenglifeng1@...wei.com>,
 "Rafael J. Wysocki" <rafael@...nel.org>
Cc: lenb@...nel.org, robert.moore@...el.com, viresh.kumar@...aro.org,
 mario.limonciello@....com, gautham.shenoy@....com, ray.huang@....com,
 acpica-devel@...ts.linux.dev, linux-acpi@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, linuxarm@...wei.com,
 yumpusamongus@...il.com, srinivas.pandruvada@...ux.intel.com,
 jonathan.cameron@...wei.com, zhanjie9@...ilicon.com, lihuisong@...wei.com,
 hepeng68@...wei.com, fanghao11@...wei.com
Subject: Re: [PATCH v5 0/8] Support for autonomous selection in cppc_cpufreq



On 2/22/25 11:07, zhenglifeng (A) wrote:
> On 2025/2/19 3:17, Rafael J. Wysocki wrote:
>> On Thu, Feb 13, 2025 at 2:55 AM zhenglifeng (A) <zhenglifeng1@...wei.com> wrote:
>>>
>>> On 2025/2/6 21:14, Lifeng Zheng wrote:
>>>> Add sysfs interfaces for CPPC autonomous selection in the cppc_cpufreq
>>>> driver.
>>>>
>>>> The patch series is organized in two parts:
>>>>
>>>>   - patch 1-5 refactor out the general CPPC register get and set functions
>>>>     in cppc_acpi.c
>>>>
>>>>   - patches 6-8 expose sysfs files for users to control CPPC autonomous
>>>>     selection when supported
>>>>
>>>> Changelog:
>>>>
>>>> v5:
>>>>
>>>>   - add more explanation to the commit logs and comments
>>>>   - change REG_OPTIONAL from bin to hex
>>>>   - split patch 2 into 3 smaller patches
>>>>   - remove CPPC_REG_VAL_READ() and CPPC_REG_VAL_WRITE() macros
>>>>   - move the modification part in patch 5 into a separate patch
>>>>   - rename the sysfs file from "energy_perf" to
>>>>     energy_performance_preference_val
>>>>
>>>> v4:
>>>>
>>>>   - add REG_OPTIONAL and IS_OPTIONAL_CPC_REG to judge if a cpc register is
>>>>     an optional one
>>>>   - check whether the register is optional before CPC_SUPPORTED check in
>>>>     cppc_get_reg_val() and cppc_set_reg_val()
>>>>   - check the register's type in cppc_set_reg_val()
>>>>   - add macros to generally implement registers getting and setting
>>>>     functions
>>>>   - move some logic codes from cppc_cpufreq.c to cppc_acpi.c
>>>>   - replace cppc_get_auto_sel_caps() by cppc_get_auto_sel()
>>>>
>>>> v3:
>>>>
>>>>   - change cppc_get_reg() and cppc_set_reg() name to cppc_get_reg_val() and
>>>>     cppc_set_reg_val()
>>>>   - extract cppc_get_reg_val_in_pcc() and cppc_set_reg_val_in_pcc()
>>>>   - return the result of cpc_read() in cppc_get_reg_val()
>>>>   - add pr_debug() in cppc_get_reg_val_in_pcc() when pcc_ss_id < 0
>>>>   - rename 'cpunum' to 'cpu' in cppc_get_reg_val()
>>>>   - move some macros from drivers/cpufreq/cppc_cpufreq.c to
>>>>     include/acpi/cppc_acpi.h with a CPPC_XXX prefix
>>>>
>>>> v2:
>>>>
>>>>   - fix some incorrect placeholder
>>>>   - change kstrtoul to kstrtobool in store_auto_select
>>>>
>>>> Lifeng Zheng (8):
>>>>    ACPI: CPPC: Add IS_OPTIONAL_CPC_REG macro to judge if a cpc_reg is
>>>>      optional
>>>>    ACPI: CPPC: Optimize cppc_get_perf()
>>>>    ACPI: CPPC: Rename cppc_get_perf() to cppc_get_reg_val()
>>>>    ACPI: CPPC: Add cppc_set_reg_val()
>>>>    ACPI: CPPC: Refactor register value get and set ABIs
>>>>    ACPI: CPPC: Modify cppc_get_auto_sel_caps() to cppc_get_auto_sel()
>>>>    ACPI: CPPC: Add three functions related to autonomous selection
>>>>    cpufreq: CPPC: Support for autonomous selection in cppc_cpufreq
>>>>
>>>>   .../ABI/testing/sysfs-devices-system-cpu      |  54 ++++
>>>>   drivers/acpi/cppc_acpi.c                      | 303 +++++++++++-------
>>>>   drivers/cpufreq/amd-pstate.c                  |   3 +-
>>>>   drivers/cpufreq/cppc_cpufreq.c                | 109 +++++++
>>>>   include/acpi/cppc_acpi.h                      |  30 +-
>>>>   5 files changed, 372 insertions(+), 127 deletions(-)
>>>>
>>>
>>> Gentle ping.
>>
>> OK, so I'm wondering how this is related to the patch series at
>>
>> https://lore.kernel.org/linux-acpi/20250211103737.447704-1-sumitg@nvidia.com/
> 
> This series refactors some cppc_acpi ABIs and supports cppc autonomous
> selection with sysfs files in cpufreq policy.  Later, [1] proposed another
> design with different user interfaces.We will discuss and reach a consensus
> with regard to this.
> 
> However, as mentioned in [1], patch 1-7 in this series (the cppc_acpi part)
> are not related to user interfaces, so can be reviewed and applied
> separately.  I can also send patch 1-7 as a new thread if preferred.
> 
> [1] https://lore.kernel.org/linux-acpi/20250211103737.447704-1-sumitg@nvidia.com/

I tried the patchset on a platform which doesn't implement CPC and everything worked well.
As Lifeng said,
   PATCH v5 8/8] cpufreq: CPPC: Support for autonomous selection in cppc_cpufreq
seems to be still in discussion, but for patches 1-7 FWIW:

Reviewed-by: Pierre Gondois <pierre.gondois@....com>

Regards,
Pierre

> 
>>
>>> Attach discussions of previous versions:
>>> v1: https://lore.kernel.org/all/20241114084816.1128647-1-zhenglifeng1@huawei.com/
>>> v2: https://lore.kernel.org/all/20241122062051.3658577-1-zhenglifeng1@huawei.com/
>>> v3: https://lore.kernel.org/all/20241216091603.1247644-1-zhenglifeng1@huawei.com/
>>> v4: https://lore.kernel.org/all/20250113122104.3870673-1-zhenglifeng1@huawei.com/
>>>
>>
> 
>