<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/cpufreq/cppc_cpufreq.c, branch v7.1-rc2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'pm-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm</title>
<updated>2026-04-14T02:47:52+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-04-14T02:47:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d7c8087a9cd8979d70edfe7c7feda9423feae3ab'/>
<id>d7c8087a9cd8979d70edfe7c7feda9423feae3ab</id>
<content type='text'>
Pull power management updates from Rafael Wysocki:
 "Once again, cpufreq is the most active development area, mostly
  because of the new feature additions and documentation updates in the
  amd-pstate driver, but there are also changes in the cpufreq core
  related to boost support and other assorted updates elsewhere.

  Next up are power capping changes due to the major cleanup of the
  Intel RAPL driver.

  On the cpuidle front, a new C-states table for Intel Panther Lake is
  added to the intel_idle driver, the stopped tick handling in the menu
  and teo governors is updated, and there are a couple of cleanups.

  Apart from the above, support for Tegra114 is added to devfreq and
  there are assorted cleanups of that code, there are also two updates
  of the operating performance points (OPP) library, two minor updates
  related to hibernation, and cpupower utility man pages updates and
  cleanups.

  Specifics:

   - Update qcom-hw DT bindings to include Eliza hardware (Abel Vesa)

   - Update cpufreq-dt-platdev blocklist (Faruque Ansari)

   - Minor updates to driver and dt-bindings for Tegra (Thierry Reding,
     Rosen Penev)

   - Add MAINTAINERS entry for CPPC driver (Viresh Kumar)

   - Add support for new features: CPPC performance priority, Dynamic
     EPP, Raw EPP, and new unit tests for them to amd-pstate (Gautham
     Shenoy, Mario Limonciello)

   - Fix sysfs files being present when HW missing and broken/outdated
     documentation in the amd-pstate driver (Ninad Naik, Gautham Shenoy)

   - Pass the policy to cpufreq_driver-&gt;adjust_perf() to avoid using
     cpufreq_cpu_get() in the .adjust_perf() callback in amd-pstate
     which leads to a scheduling-while-atomic bug (K Prateek Nayak)

   - Clean up dead code in Kconfig for cpufreq (Julian Braha)

   - Remove max_freq_req update for pre-existing cpufreq policy and add
     a boost_freq_req QoS request to save the boost constraint instead
     of overwriting the last scaling_max_freq constraint (Pierre
     Gondois)

   - Embed cpufreq QoS freq_req objects in cpufreq policy so they all
     are allocated in one go along with the policy to simplify lifetime
     rules and avoid error handling issues (Viresh Kumar)

   - Use DMI max speed when CPPC is unavailable in the acpi-cpufreq
     scaling driver (Henry Tseng)

   - Switch policy_is_shared() in cpufreq to using cpumask_nth() instead
     of cpumask_weight() because the former is more efficient (Yury
     Norov)

   - Use sysfs_emit() in sysfs show functions for cpufreq governor
     attributes (Thorsten Blum)

   - Update intel_pstate to stop returning an error when "off" is
     written to its status sysfs attribute while the driver is already
     off (Fabio De Francesco)

   - Include current frequency in the debug message printed by
     __cpufreq_driver_target() (Pengjie Zhang)

   - Refine stopped tick handling in the menu cpuidle governor and
     rearrange stopped tick handling in the teo cpuidle governor (Rafael
     Wysocki)

   - Add Panther Lake C-states table to the intel_idle driver (Artem
     Bityutskiy)

   - Clean up dead dependencies on CPU_IDLE in Kconfig (Julian Braha)

   - Simplify cpuidle_register_device() with guard() (Huisong Li)

   - Use performance level if available to distinguish between rates in
     OPP debugfs (Manivannan Sadhasivam)

   - Fix scoped_guard in dev_pm_opp_xlate_required_opp() (Viresh Kumar)

   - Return -ENODATA if the snapshot image is not loaded (Alberto
     Garcia)

   - Remove inclusion of crypto/hash.h from hibernate_64.c on x86 (Eric
     Biggers)

   - Clean up and rearrange the intel_rapl power capping driver to make
     the respective interface drivers (TPMI, MSR, and MMOI) hold their
     own settings and primitives and consolidate PL4 and PMU support
     flags into rapl_defaults (Kuppuswamy Sathyanarayanan)

   - Correct kernel-doc function parameter names in the power capping
     core code (Randy Dunlap)

   - Remove unneeded casting for HZ_PER_KHZ in devfreq (Andy Shevchenko)

   - Use _visible attribute to replace create/remove_sysfs_files() in
     devfreq (Pengjie Zhang)

   - Add Tegra114 support to activity monitor device in tegra30-devfreq
     as a preparation to upcoming EMC controller support (Svyatoslav
     Ryhel)

   - Fix mistakes in cpupower man pages, add the boost and epp options
     to the cpupower-frequency-info man page, and add the perf-bias
     option to the cpupower-info man page (Roberto Ricci)

   - Remove unnecessary extern declarations from getopt.h in arguments
     parsing functions in cpufreq-set, cpuidle-info, cpuidle-set,
     cpupower-info, and cpupower-set utilities (Kaushlendra Kumar)"

* tag 'pm-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (74 commits)
  cpufreq/amd-pstate: Add POWER_SUPPLY select for dynamic EPP
  cpupower: remove extern declarations in cmd functions
  cpuidle: Simplify cpuidle_register_device() with guard()
  PM / devfreq: tegra30-devfreq: add support for Tegra114
  PM / devfreq: use _visible attribute to replace create/remove_sysfs_files()
  PM / devfreq: Remove unneeded casting for HZ_PER_KHZ
  MAINTAINERS: amd-pstate: Step down as maintainer, add Prateek as reviewer
  cpufreq: Pass the policy to cpufreq_driver-&gt;adjust_perf()
  cpufreq/amd-pstate: Pass the policy to amd_pstate_update()
  cpufreq/amd-pstate-ut: Add a unit test for raw EPP
  cpufreq/amd-pstate: Add support for raw EPP writes
  cpufreq/amd-pstate: Add support for platform profile class
  cpufreq/amd-pstate: add kernel command line to override dynamic epp
  cpufreq/amd-pstate: Add dynamic energy performance preference
  Documentation: amd-pstate: fix dead links in the reference section
  cpufreq/amd-pstate: Cache the max frequency in cpudata
  Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}
  Documentation/amd-pstate: List amd_pstate_prefcore_ranking sysfs file
  Documentation/amd-pstate: List amd_pstate_hw_prefcore sysfs file
  amd-pstate-ut: Add a testcase to validate the visibility of driver attributes
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull power management updates from Rafael Wysocki:
 "Once again, cpufreq is the most active development area, mostly
  because of the new feature additions and documentation updates in the
  amd-pstate driver, but there are also changes in the cpufreq core
  related to boost support and other assorted updates elsewhere.

  Next up are power capping changes due to the major cleanup of the
  Intel RAPL driver.

  On the cpuidle front, a new C-states table for Intel Panther Lake is
  added to the intel_idle driver, the stopped tick handling in the menu
  and teo governors is updated, and there are a couple of cleanups.

  Apart from the above, support for Tegra114 is added to devfreq and
  there are assorted cleanups of that code, there are also two updates
  of the operating performance points (OPP) library, two minor updates
  related to hibernation, and cpupower utility man pages updates and
  cleanups.

  Specifics:

   - Update qcom-hw DT bindings to include Eliza hardware (Abel Vesa)

   - Update cpufreq-dt-platdev blocklist (Faruque Ansari)

   - Minor updates to driver and dt-bindings for Tegra (Thierry Reding,
     Rosen Penev)

   - Add MAINTAINERS entry for CPPC driver (Viresh Kumar)

   - Add support for new features: CPPC performance priority, Dynamic
     EPP, Raw EPP, and new unit tests for them to amd-pstate (Gautham
     Shenoy, Mario Limonciello)

   - Fix sysfs files being present when HW missing and broken/outdated
     documentation in the amd-pstate driver (Ninad Naik, Gautham Shenoy)

   - Pass the policy to cpufreq_driver-&gt;adjust_perf() to avoid using
     cpufreq_cpu_get() in the .adjust_perf() callback in amd-pstate
     which leads to a scheduling-while-atomic bug (K Prateek Nayak)

   - Clean up dead code in Kconfig for cpufreq (Julian Braha)

   - Remove max_freq_req update for pre-existing cpufreq policy and add
     a boost_freq_req QoS request to save the boost constraint instead
     of overwriting the last scaling_max_freq constraint (Pierre
     Gondois)

   - Embed cpufreq QoS freq_req objects in cpufreq policy so they all
     are allocated in one go along with the policy to simplify lifetime
     rules and avoid error handling issues (Viresh Kumar)

   - Use DMI max speed when CPPC is unavailable in the acpi-cpufreq
     scaling driver (Henry Tseng)

   - Switch policy_is_shared() in cpufreq to using cpumask_nth() instead
     of cpumask_weight() because the former is more efficient (Yury
     Norov)

   - Use sysfs_emit() in sysfs show functions for cpufreq governor
     attributes (Thorsten Blum)

   - Update intel_pstate to stop returning an error when "off" is
     written to its status sysfs attribute while the driver is already
     off (Fabio De Francesco)

   - Include current frequency in the debug message printed by
     __cpufreq_driver_target() (Pengjie Zhang)

   - Refine stopped tick handling in the menu cpuidle governor and
     rearrange stopped tick handling in the teo cpuidle governor (Rafael
     Wysocki)

   - Add Panther Lake C-states table to the intel_idle driver (Artem
     Bityutskiy)

   - Clean up dead dependencies on CPU_IDLE in Kconfig (Julian Braha)

   - Simplify cpuidle_register_device() with guard() (Huisong Li)

   - Use performance level if available to distinguish between rates in
     OPP debugfs (Manivannan Sadhasivam)

   - Fix scoped_guard in dev_pm_opp_xlate_required_opp() (Viresh Kumar)

   - Return -ENODATA if the snapshot image is not loaded (Alberto
     Garcia)

   - Remove inclusion of crypto/hash.h from hibernate_64.c on x86 (Eric
     Biggers)

   - Clean up and rearrange the intel_rapl power capping driver to make
     the respective interface drivers (TPMI, MSR, and MMOI) hold their
     own settings and primitives and consolidate PL4 and PMU support
     flags into rapl_defaults (Kuppuswamy Sathyanarayanan)

   - Correct kernel-doc function parameter names in the power capping
     core code (Randy Dunlap)

   - Remove unneeded casting for HZ_PER_KHZ in devfreq (Andy Shevchenko)

   - Use _visible attribute to replace create/remove_sysfs_files() in
     devfreq (Pengjie Zhang)

   - Add Tegra114 support to activity monitor device in tegra30-devfreq
     as a preparation to upcoming EMC controller support (Svyatoslav
     Ryhel)

   - Fix mistakes in cpupower man pages, add the boost and epp options
     to the cpupower-frequency-info man page, and add the perf-bias
     option to the cpupower-info man page (Roberto Ricci)

   - Remove unnecessary extern declarations from getopt.h in arguments
     parsing functions in cpufreq-set, cpuidle-info, cpuidle-set,
     cpupower-info, and cpupower-set utilities (Kaushlendra Kumar)"

* tag 'pm-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (74 commits)
  cpufreq/amd-pstate: Add POWER_SUPPLY select for dynamic EPP
  cpupower: remove extern declarations in cmd functions
  cpuidle: Simplify cpuidle_register_device() with guard()
  PM / devfreq: tegra30-devfreq: add support for Tegra114
  PM / devfreq: use _visible attribute to replace create/remove_sysfs_files()
  PM / devfreq: Remove unneeded casting for HZ_PER_KHZ
  MAINTAINERS: amd-pstate: Step down as maintainer, add Prateek as reviewer
  cpufreq: Pass the policy to cpufreq_driver-&gt;adjust_perf()
  cpufreq/amd-pstate: Pass the policy to amd_pstate_update()
  cpufreq/amd-pstate-ut: Add a unit test for raw EPP
  cpufreq/amd-pstate: Add support for raw EPP writes
  cpufreq/amd-pstate: Add support for platform profile class
  cpufreq/amd-pstate: add kernel command line to override dynamic epp
  cpufreq/amd-pstate: Add dynamic energy performance preference
  Documentation: amd-pstate: fix dead links in the reference section
  cpufreq/amd-pstate: Cache the max frequency in cpudata
  Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}
  Documentation/amd-pstate: List amd_pstate_prefcore_ranking sysfs file
  Documentation/amd-pstate: List amd_pstate_hw_prefcore sysfs file
  amd-pstate-ut: Add a testcase to validate the visibility of driver attributes
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: Add boost_freq_req QoS request</title>
<updated>2026-03-30T19:56:52+00:00</updated>
<author>
<name>Pierre Gondois</name>
<email>pierre.gondois@arm.com</email>
</author>
<published>2026-03-26T20:44:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6e39ba4e5a82aa5469b2ac517b74a71accb0540f'/>
<id>6e39ba4e5a82aa5469b2ac517b74a71accb0540f</id>
<content type='text'>
The Power Management Quality of Service (PM QoS) allows to
aggregate constraints from multiple entities. It is currently
used to manage the min/max frequency of a given policy.

Frequency constraints can come for instance from:
 - Thermal framework: acpi_thermal_cpufreq_init()
 - Firmware: _PPC objects: acpi_processor_ppc_init()
 - User: by setting policyX/scaling_[min|max]_freq
The minimum of the max frequency constraints is used to compute
the resulting maximum allowed frequency.

When enabling boost frequencies, the same frequency request object
(policy-&gt;max_freq_req) as to handle requests from users is used.
As a result, when setting:
 - scaling_max_freq
 - boost
The last sysfs file used overwrites the request from the other
sysfs file.

To avoid this, create a per-policy boost_freq_req to save the boost
constraints instead of overwriting the last scaling_max_freq
constraint.

policy_set_boost() calls the cpufreq set_boost callback.
Update the newly added boost_freq_req request from there:
 - whenever boost is toggled
 - to cover all possible paths

In the existing .set_boost() callbacks:
 - Don't update policy-&gt;max as this is done through the qos notifier
   cpufreq_notifier_max() which calls cpufreq_set_policy().
 - Remove freq_qos_update_request() calls as the qos request is now
   done in policy_set_boost() and updates the new boost_freq_req

$ ## Init state
scaling_max_freq:1000000
cpuinfo_max_freq:1000000

$ echo 700000 &gt; scaling_max_freq
scaling_max_freq:700000
cpuinfo_max_freq:1000000

$ echo 1 &gt; ../boost
scaling_max_freq:1200000
cpuinfo_max_freq:1200000

$ echo 800000 &gt; scaling_max_freq
scaling_max_freq:800000
cpuinfo_max_freq:1200000

$ ## Final step:
$ ## Without the patches:
$ echo 0 &gt; ../boost
scaling_max_freq:1000000
cpuinfo_max_freq:1000000

$ ## With the patches:
$ echo 0 &gt; ../boost
scaling_max_freq:800000
cpuinfo_max_freq:1000000

Note:
cpufreq_frequency_table_cpuinfo() updates policy-&gt;min
and max from:
A.
cpufreq_boost_set_sw()
\-cpufreq_frequency_table_cpuinfo()
B.
cpufreq_policy_online()
\-cpufreq_table_validate_and_sort()
  \-cpufreq_frequency_table_cpuinfo()
Keep these updates as some drivers expect policy-&gt;min and
max to be set through B.

Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Signed-off-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Acked-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Link: https://patch.msgid.link/20260326204404.1401849-3-pierre.gondois@arm.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The Power Management Quality of Service (PM QoS) allows to
aggregate constraints from multiple entities. It is currently
used to manage the min/max frequency of a given policy.

Frequency constraints can come for instance from:
 - Thermal framework: acpi_thermal_cpufreq_init()
 - Firmware: _PPC objects: acpi_processor_ppc_init()
 - User: by setting policyX/scaling_[min|max]_freq
The minimum of the max frequency constraints is used to compute
the resulting maximum allowed frequency.

When enabling boost frequencies, the same frequency request object
(policy-&gt;max_freq_req) as to handle requests from users is used.
As a result, when setting:
 - scaling_max_freq
 - boost
The last sysfs file used overwrites the request from the other
sysfs file.

To avoid this, create a per-policy boost_freq_req to save the boost
constraints instead of overwriting the last scaling_max_freq
constraint.

policy_set_boost() calls the cpufreq set_boost callback.
Update the newly added boost_freq_req request from there:
 - whenever boost is toggled
 - to cover all possible paths

In the existing .set_boost() callbacks:
 - Don't update policy-&gt;max as this is done through the qos notifier
   cpufreq_notifier_max() which calls cpufreq_set_policy().
 - Remove freq_qos_update_request() calls as the qos request is now
   done in policy_set_boost() and updates the new boost_freq_req

$ ## Init state
scaling_max_freq:1000000
cpuinfo_max_freq:1000000

$ echo 700000 &gt; scaling_max_freq
scaling_max_freq:700000
cpuinfo_max_freq:1000000

$ echo 1 &gt; ../boost
scaling_max_freq:1200000
cpuinfo_max_freq:1200000

$ echo 800000 &gt; scaling_max_freq
scaling_max_freq:800000
cpuinfo_max_freq:1200000

$ ## Final step:
$ ## Without the patches:
$ echo 0 &gt; ../boost
scaling_max_freq:1000000
cpuinfo_max_freq:1000000

$ ## With the patches:
$ echo 0 &gt; ../boost
scaling_max_freq:800000
cpuinfo_max_freq:1000000

Note:
cpufreq_frequency_table_cpuinfo() updates policy-&gt;min
and max from:
A.
cpufreq_boost_set_sw()
\-cpufreq_frequency_table_cpuinfo()
B.
cpufreq_policy_online()
\-cpufreq_table_validate_and_sort()
  \-cpufreq_frequency_table_cpuinfo()
Keep these updates as some drivers expect policy-&gt;min and
max to be set through B.

Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Signed-off-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Acked-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Link: https://patch.msgid.link/20260326204404.1401849-3-pierre.gondois@arm.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI: CPPC: Move reference performance to capabilities</title>
<updated>2026-03-05T19:00:19+00:00</updated>
<author>
<name>Pengjie Zhang</name>
<email>zhangpengjie2@huawei.com</email>
</author>
<published>2026-02-13T10:09:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8505bfb4e4eca28ef1b20d3369435ec2d6a125c6'/>
<id>8505bfb4e4eca28ef1b20d3369435ec2d6a125c6</id>
<content type='text'>
Currently, the `Reference Performance` register is read every time
the CPU frequency is sampled in `cppc_get_perf_ctrs()`. This function
is on the hot path of the cppc_cpufreq driver.

Reference Performance indicates the performance level that corresponds
to the Reference Counter incrementing and is not expected to change
dynamically during runtime (unlike the Delivered and Reference counters).

Reading this register in the hot path incurs unnecessary overhead,
particularly on platforms where CPC registers are located in the PCC
(Platform Communication Channel) subspace. This patch moves
`reference_perf` from the dynamic feedback counters structure
(`cppc_perf_fb_ctrs`) to the static capabilities structure
(`cppc_perf_caps`).

Signed-off-by: Pengjie Zhang &lt;zhangpengjie2@huawei.com&gt;
[ rjw: Changelog adjustment ]
Link: https://patch.msgid.link/20260213100935.19111-1-zhangpengjie2@huawei.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently, the `Reference Performance` register is read every time
the CPU frequency is sampled in `cppc_get_perf_ctrs()`. This function
is on the hot path of the cppc_cpufreq driver.

Reference Performance indicates the performance level that corresponds
to the Reference Counter incrementing and is not expected to change
dynamically during runtime (unlike the Delivered and Reference counters).

Reading this register in the hot path incurs unnecessary overhead,
particularly on platforms where CPC registers are located in the PCC
(Platform Communication Channel) subspace. This patch moves
`reference_perf` from the dynamic feedback counters structure
(`cppc_perf_fb_ctrs`) to the static capabilities structure
(`cppc_perf_caps`).

Signed-off-by: Pengjie Zhang &lt;zhangpengjie2@huawei.com&gt;
[ rjw: Changelog adjustment ]
Link: https://patch.msgid.link/20260213100935.19111-1-zhangpengjie2@huawei.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI: CPPC: add APIs and sysfs interface for perf_limited</title>
<updated>2026-02-27T19:50:42+00:00</updated>
<author>
<name>Sumit Gupta</name>
<email>sumitg@nvidia.com</email>
</author>
<published>2026-02-06T14:26:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=13c45a26635fa51a68911aa57e6778bdad18b103'/>
<id>13c45a26635fa51a68911aa57e6778bdad18b103</id>
<content type='text'>
Add sysfs interface to read/write the Performance Limited register.

The Performance Limited register indicates to the OS that an
unpredictable event (like thermal throttling) has limited processor
performance. It contains two sticky bits set by the platform:
  - Bit 0 (Desired_Excursion): Set when delivered performance is
    constrained below desired performance. Not used when Autonomous
    Selection is enabled.
  - Bit 1 (Minimum_Excursion): Set when delivered performance is
    constrained below minimum performance.

These bits remain set until OSPM explicitly clears them. The write
operation accepts a bitmask of bits to clear:
  - Write 0x1 to clear bit 0
  - Write 0x2 to clear bit 1
  - Write 0x3 to clear both bits

This enables users to detect if platform throttling impacted a workload.
Users clear the register before execution, run the workload, then check
afterward - if set, hardware throttling occurred during that time window.

The interface is exposed as:
  /sys/devices/system/cpu/cpuX/cpufreq/perf_limited

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-7-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add sysfs interface to read/write the Performance Limited register.

The Performance Limited register indicates to the OS that an
unpredictable event (like thermal throttling) has limited processor
performance. It contains two sticky bits set by the platform:
  - Bit 0 (Desired_Excursion): Set when delivered performance is
    constrained below desired performance. Not used when Autonomous
    Selection is enabled.
  - Bit 1 (Minimum_Excursion): Set when delivered performance is
    constrained below minimum performance.

These bits remain set until OSPM explicitly clears them. The write
operation accepts a bitmask of bits to clear:
  - Write 0x1 to clear bit 0
  - Write 0x2 to clear bit 1
  - Write 0x3 to clear both bits

This enables users to detect if platform throttling impacted a workload.
Users clear the register before execution, run the workload, then check
afterward - if set, hardware throttling occurred during that time window.

The interface is exposed as:
  /sys/devices/system/cpu/cpuX/cpufreq/perf_limited

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-7-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: cppc: Update MIN_PERF/MAX_PERF in target callbacks</title>
<updated>2026-02-27T19:50:42+00:00</updated>
<author>
<name>Sumit Gupta</name>
<email>sumitg@nvidia.com</email>
</author>
<published>2026-02-06T14:26:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ea3db45ae476889a1ba0ab3617e6afdeeefbda3d'/>
<id>ea3db45ae476889a1ba0ab3617e6afdeeefbda3d</id>
<content type='text'>
Update MIN_PERF and MAX_PERF registers from policy-&gt;min and policy-&gt;max
in the .target() and .fast_switch() callbacks. This allows controlling
performance bounds via standard scaling_min_freq and scaling_max_freq
sysfs interfaces.

Similar to intel_cpufreq which updates HWP min/max limits in .target(),
cppc_cpufreq now programs MIN_PERF/MAX_PERF along with DESIRED_PERF.
Since MIN_PERF/MAX_PERF can be updated even when auto_sel is disabled,
they are updated unconditionally.

Also program MIN_PERF/MAX_PERF in store_auto_select() when enabling
autonomous selection so the platform uses correct bounds immediately.

Suggested-by: Rafael J. Wysocki &lt;rafael@kernel.org&gt;
Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-6-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Update MIN_PERF and MAX_PERF registers from policy-&gt;min and policy-&gt;max
in the .target() and .fast_switch() callbacks. This allows controlling
performance bounds via standard scaling_min_freq and scaling_max_freq
sysfs interfaces.

Similar to intel_cpufreq which updates HWP min/max limits in .target(),
cppc_cpufreq now programs MIN_PERF/MAX_PERF along with DESIRED_PERF.
Since MIN_PERF/MAX_PERF can be updated even when auto_sel is disabled,
they are updated unconditionally.

Also program MIN_PERF/MAX_PERF in store_auto_select() when enabling
autonomous selection so the platform uses correct bounds immediately.

Suggested-by: Rafael J. Wysocki &lt;rafael@kernel.org&gt;
Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-6-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: CPPC: Update cached perf_ctrls on sysfs write</title>
<updated>2026-02-27T19:50:42+00:00</updated>
<author>
<name>Sumit Gupta</name>
<email>sumitg@nvidia.com</email>
</author>
<published>2026-02-06T14:26:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=24ad4c6c136bdaa4c92c5c5948856752ce3e9f76'/>
<id>24ad4c6c136bdaa4c92c5c5948856752ce3e9f76</id>
<content type='text'>
Update the cached perf_ctrls values when writing via sysfs to keep
them in sync with hardware registers:
- store_auto_select(): update perf_ctrls.auto_sel
- store_energy_performance_preference_val(): update perf_ctrls.energy_perf

This ensures consistent cached values after sysfs writes, which
complements the cppc_get_perf() initialization during policy setup.

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-5-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Update the cached perf_ctrls values when writing via sysfs to keep
them in sync with hardware registers:
- store_auto_select(): update perf_ctrls.auto_sel
- store_energy_performance_preference_val(): update perf_ctrls.energy_perf

This ensures consistent cached values after sysfs writes, which
complements the cppc_get_perf() initialization during policy setup.

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-5-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ACPI: CPPC: Add cppc_get_perf() API to read performance controls</title>
<updated>2026-02-27T19:50:41+00:00</updated>
<author>
<name>Sumit Gupta</name>
<email>sumitg@nvidia.com</email>
</author>
<published>2026-02-06T14:26:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=658fa7b1c47a857af484c5c5dff8d0164b7c7bfb'/>
<id>658fa7b1c47a857af484c5c5dff8d0164b7c7bfb</id>
<content type='text'>
Add cppc_get_perf() function to read values of performance control
registers including desired_perf, min_perf, max_perf, energy_perf,
and auto_sel.

This provides a read interface to complement the existing
cppc_set_perf() write interface for performance control registers.

Note that auto_sel is read by cppc_get_perf() but not written by
cppc_set_perf() to avoid unintended mode changes during performance
updates. It can be updated with existing dedicated cppc_set_auto_sel()
API.

Use cppc_get_perf() in cppc_cpufreq_get_cpu_data() to initialize
perf_ctrls with current hardware register values during cpufreq
policy initialization.

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-2-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add cppc_get_perf() function to read values of performance control
registers including desired_perf, min_perf, max_perf, energy_perf,
and auto_sel.

This provides a read interface to complement the existing
cppc_set_perf() write interface for performance control registers.

Note that auto_sel is read by cppc_get_perf() but not written by
cppc_set_perf() to avoid unintended mode changes during performance
updates. It can be updated with existing dedicated cppc_set_auto_sel()
API.

Use cppc_get_perf() in cppc_cpufreq_get_cpu_data() to initialize
perf_ctrls with current hardware register values during cpufreq
policy initialization.

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Pierre Gondois &lt;pierre.gondois@arm.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
Link: https://patch.msgid.link/20260206142658.72583-2-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Convert 'alloc_obj' family to use the new default GFP_KERNEL argument</title>
<updated>2026-02-22T01:09:51+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-02-22T00:37:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43'/>
<id>bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43</id>
<content type='text'>
This was done entirely with mindless brute force, using

    git grep -l '\&lt;k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This was done entirely with mindless brute force, using

    git grep -l '\&lt;k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: Replace kmalloc with kmalloc_obj for non-scalar types</title>
<updated>2026-02-21T09:02:28+00:00</updated>
<author>
<name>Kees Cook</name>
<email>kees@kernel.org</email>
</author>
<published>2026-02-21T07:49:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=69050f8d6d075dc01af7a5f2f550a8067510366f'/>
<id>69050f8d6d075dc01af7a5f2f550a8067510366f</id>
<content type='text'>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: CPPC: Add generic helpers for sysfs show/store</title>
<updated>2026-01-28T18:10:50+00:00</updated>
<author>
<name>Sumit Gupta</name>
<email>sumitg@nvidia.com</email>
</author>
<published>2026-01-20T14:56:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=4a1cf5ed51b1b6049d7771d2e77789b99dafc8ae'/>
<id>4a1cf5ed51b1b6049d7771d2e77789b99dafc8ae</id>
<content type='text'>
Add generic helper functions for u64 sysfs attributes that follow the
common pattern of calling CPPC get/set APIs:
 - cppc_cpufreq_sysfs_show_u64(): reads value and handles -EOPNOTSUPP
 - cppc_cpufreq_sysfs_store_u64(): parses input and calls set function

Add CPPC_CPUFREQ_ATTR_RW_U64() macro to generate show/store functions
using these helpers, reducing boilerplate for simple attributes.

Convert auto_act_window and energy_performance_preference_val to use
the new macro.

No functional changes.

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
[ rjw: Retained empty code line after a conditional ]
Link: https://patch.msgid.link/20260120145623.2959636-2-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add generic helper functions for u64 sysfs attributes that follow the
common pattern of calling CPPC get/set APIs:
 - cppc_cpufreq_sysfs_show_u64(): reads value and handles -EOPNOTSUPP
 - cppc_cpufreq_sysfs_store_u64(): parses input and calls set function

Add CPPC_CPUFREQ_ATTR_RW_U64() macro to generate show/store functions
using these helpers, reducing boilerplate for simple attributes.

Convert auto_act_window and energy_performance_preference_val to use
the new macro.

No functional changes.

Signed-off-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Reviewed-by: Lifeng Zheng &lt;zhenglifeng1@huawei.com&gt;
[ rjw: Retained empty code line after a conditional ]
Link: https://patch.msgid.link/20260120145623.2959636-2-sumitg@nvidia.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
