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[PATCH v5 07/11] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited

Sumit Gupta posted 11 patches 1 month, 2 weeks ago
There is a newer version of this series
[PATCH v5 07/11] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited
Posted by Sumit Gupta 1 month, 2 weeks ago 
Add sysfs interfaces for Minimum Performance, Maximum Performance
and Performance Limited Register in the cppc_cpufreq driver.

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 .../ABI/testing/sysfs-devices-system-cpu      | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 3a05604c21bf..b022cbf46adc 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -327,6 +327,48 @@ Description:	Energy performance preference
 
 		This file is only present if the cppc-cpufreq driver is in use.
 
+What:		/sys/devices/system/cpu/cpuX/cpufreq/min_perf
+Date:		February 2026
+Contact:	linux-pm@vger.kernel.org
+Description:	Minimum Performance Frequency
+
+		Read/write a frequency value in kHz from/to this file. This
+		file sets the minimum performance level (as frequency) at
+		which the platform may run. The frequency value is internally
+		converted to a performance value and must be in the range
+		[cpuinfo_min_freq, cpuinfo_max_freq], inclusive.
+
+		This file is only present if the cppc-cpufreq driver is in use.
+
+What:		/sys/devices/system/cpu/cpuX/cpufreq/max_perf
+Date:		February 2026
+Contact:	linux-pm@vger.kernel.org
+Description:	Maximum Performance Frequency
+
+		Read/write a frequency value in kHz from/to this file. This
+		file sets the maximum performance level (as frequency) at
+		which the platform may run. The frequency value is internally
+		converted to a performance value and must be in the range
+		[cpuinfo_min_freq, cpuinfo_max_freq], inclusive.
+
+		This file is only present if the cppc-cpufreq driver is in use.
+
+What:		/sys/devices/system/cpu/cpuX/cpufreq/perf_limited
+Date:		February 2026
+Contact:	linux-pm@vger.kernel.org
+Description:	Performance Limited
+
+		Read to check if platform throttling (thermal/power/current
+		limits) caused delivered performance to fall below the
+		requested level. A non-zero value indicates throttling occurred.
+
+		Write the bitmask of bits to clear:
+		  1 = clear bit 0 (desired performance excursion)
+		  2 = clear bit 1 (minimum performance excursion)
+		  3 = clear both bits
+		The platform sets these bits; OSPM can only clear them.
+
+		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
-- 
2.34.1
Re: [PATCH v5 07/11] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited
Posted by Bagas Sanjaya 1 month, 2 weeks ago 
On Tue, Dec 23, 2025 at 05:43:03PM +0530, Sumit Gupta wrote:
> +		Write the bitmask of bits to clear:
> +		  1 = clear bit 0 (desired performance excursion)
> +		  2 = clear bit 1 (minimum performance excursion)
> +		  3 = clear both bits
> +		The platform sets these bits; OSPM can only clear them.

Sphinx reports htmldocs warning:

Documentation/ABI/testing/sysfs-devices-system-cpu:356: WARNING: Definition list ends without a blank line; unexpected unindent. [docutils]

I have to fix up the bitmask list:

---- >8 ----
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index b022cbf46adcfe..8cda698019922b 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -363,9 +363,11 @@ Description:	Performance Limited
 		requested level. A non-zero value indicates throttling occurred.
 
 		Write the bitmask of bits to clear:
-		  1 = clear bit 0 (desired performance excursion)
-		  2 = clear bit 1 (minimum performance excursion)
-		  3 = clear both bits
+
+		- 1 = clear bit 0 (desired performance excursion)
+		- 2 = clear bit 1 (minimum performance excursion)
+		- 3 = clear both bits
+
 		The platform sets these bits; OSPM can only clear them.
 
 		This file is only present if the cppc-cpufreq driver is in use.

Thanks.

-- 
An old man doll... just what I always wanted! - Clara
Re: [PATCH v5 07/11] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited
Posted by Sumit Gupta 1 month ago 
On 26/12/25 05:50, Bagas Sanjaya wrote:
> On Tue, Dec 23, 2025 at 05:43:03PM +0530, Sumit Gupta wrote:
>> +		Write the bitmask of bits to clear:
>> +		  1 = clear bit 0 (desired performance excursion)
>> +		  2 = clear bit 1 (minimum performance excursion)
>> +		  3 = clear both bits
>> +		The platform sets these bits; OSPM can only clear them.
> Sphinx reports htmldocs warning:
>
> Documentation/ABI/testing/sysfs-devices-system-cpu:356: WARNING: Definition list ends without a blank line; unexpected unindent. [docutils]
>
> I have to fix up the bitmask list:
>
> ---- >8 ----
> diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
> index b022cbf46adcfe..8cda698019922b 100644
> --- a/Documentation/ABI/testing/sysfs-devices-system-cpu
> +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
> @@ -363,9 +363,11 @@ Description:	Performance Limited
>   		requested level. A non-zero value indicates throttling occurred.
>   
>   		Write the bitmask of bits to clear:
> -		  1 = clear bit 0 (desired performance excursion)
> -		  2 = clear bit 1 (minimum performance excursion)
> -		  3 = clear both bits
> +
> +		- 1 = clear bit 0 (desired performance excursion)
> +		- 2 = clear bit 1 (minimum performance excursion)
> +		- 3 = clear both bits
> +
>   		The platform sets these bits; OSPM can only clear them.
>   
>   		This file is only present if the cppc-cpufreq driver is in use.
>
> Thanks.
>

Thanks for the change.
Re: [PATCH v5 07/11] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited
Posted by kernel test robot 1 month, 2 weeks ago 
Hi Sumit,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rafael-pm/linux-next]
[also build test WARNING on rafael-pm/bleeding-edge linus/master v6.19-rc2 next-20251219]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sumit-Gupta/cpufreq-CPPC-Add-generic-helpers-for-sysfs-show-store/20251224-001833
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
patch link:    https://lore.kernel.org/r/20251223121307.711773-8-sumitg%40nvidia.com
patch subject: [PATCH v5 07/11] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited
reproduce: (https://download.01.org/0day-ci/archive/20251224/202512241930.heuhsbt9-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512241930.heuhsbt9-lkp@intel.com/

All warnings (new ones prefixed by >>):

   Using alabaster theme
   ERROR: Cannot find file ./include/linux/pci.h
   WARNING: No kernel-doc for file ./include/linux/pci.h
   ERROR: Cannot find file ./include/linux/mod_devicetable.h
   WARNING: No kernel-doc for file ./include/linux/mod_devicetable.h
>> Documentation/ABI/testing/sysfs-devices-system-cpu:356: WARNING: Definition list ends without a blank line; unexpected unindent. [docutils]
   ERROR: Cannot find file ./include/linux/bootconfig.h
   WARNING: No kernel-doc for file ./include/linux/bootconfig.h
   ERROR: Cannot find file ./include/linux/pstore_zone.h
   ERROR: Cannot find file ./include/linux/pstore_zone.h
   WARNING: No kernel-doc for file ./include/linux/pstore_zone.h


vim +356 Documentation/ABI/testing/sysfs-devices-system-cpu

   347	
   348			Read/write a frequency value in kHz from/to this file. This
   349			file sets the maximum performance level (as frequency) at
   350			which the platform may run. The frequency value is internally
   351			converted to a performance value and must be in the range
   352			[cpuinfo_min_freq, cpuinfo_max_freq], inclusive.
   353	
   354			This file is only present if the cppc-cpufreq driver is in use.
   355	
 > 356	What:		/sys/devices/system/cpu/cpuX/cpufreq/perf_limited
   357	Date:		February 2026
   358	Contact:	linux-pm@vger.kernel.org
   359	Description:	Performance Limited
   360	
   361			Read to check if platform throttling (thermal/power/current
   362			limits) caused delivered performance to fall below the
   363			requested level. A non-zero value indicates throttling occurred.
   364	
   365			Write the bitmask of bits to clear:
   366			  1 = clear bit 0 (desired performance excursion)
   367			  2 = clear bit 1 (minimum performance excursion)
   368			  3 = clear both bits
   369			The platform sets these bits; OSPM can only clear them.
   370	
   371			This file is only present if the cppc-cpufreq driver is in use.
   372	

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