linux.git/drivers/cpufreq, branch v7.1-rc5 Linux kernel source tree Merge tag 'amd-pstate-v7.1-2026-05-14' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/superm1/linux into pm-cpufreq-fixes 2026-05-20T20:03:41+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2026-05-20T20:03:41+00:00 a67f3113331d9fb3eb0664602d9b581cb2df7294 Merge amd-pstate fixes for 7.1 (05/14/2026) from Mario Limonciello: "A number of fixes to the dynamic epp feature which was new to kernel 7.1, including making it opt in only." * tag 'amd-pstate-v7.1-2026-05-14' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/superm1/linux: cpufreq/amd-pstate: Drop Kconfig option for dynamic EPP cpufreq/amd-pstate-ut: Drop policy reference before driver switch cpufreq/amd-pstate: Use "epp_default_dc" as default when dynamic_epp is disabled cpufreq/amd-pstate: Reorder notifier unregistration and floor perf reset cpufreq/amd-pstate: Allow writes to dynamic_epp when state isn't modified cpufreq/amd-pstate: Return -ENOMEM on failure to allocate profile_name cpufreq/amd-pstate: Grab "amd_pstate_driver_lock" when toggling dynamic_epp 
Merge amd-pstate fixes for 7.1 (05/14/2026) from Mario Limonciello:

"A number of fixes to the dynamic epp feature which was new
 to kernel 7.1, including making it opt in only."

* tag 'amd-pstate-v7.1-2026-05-14' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/superm1/linux:
  cpufreq/amd-pstate: Drop Kconfig option for dynamic EPP
  cpufreq/amd-pstate-ut: Drop policy reference before driver switch
  cpufreq/amd-pstate: Use "epp_default_dc" as default when dynamic_epp is disabled
  cpufreq/amd-pstate: Reorder notifier unregistration and floor perf reset
  cpufreq/amd-pstate: Allow writes to dynamic_epp when state isn't modified
  cpufreq/amd-pstate: Return -ENOMEM on failure to allocate profile_name
  cpufreq/amd-pstate: Grab "amd_pstate_driver_lock" when toggling dynamic_epp
cpufreq/amd-pstate: Drop Kconfig option for dynamic EPP 2026-05-14T13:47:48+00:00 Mario Limonciello mario.limonciello@amd.com 2026-05-12T22:19:47+00:00 e4e9b7b38d5db2cc6a8770bc0596bb8b36b92b1f There are some performance issues being identified by dynamic EPP and we don't want to have distributions turning it on by default exposing them to users at this time. Drop the kconfig option, and require an explicit opt in from kernel command line or runtime sysfs option to turn it on. Reported-by: Viktor Jägersküpper <viktor_jaegerskuepper@freenet.de> Closes: https://lore.kernel.org/linux-pm/14a87c99-785c-4b16-bfce-35ecbf053448@freenet.de/ Reported-by: Stuart Meckle <stuartmeckle@gmail.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221473 Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20260512221947.1652988-1-mario.limonciello@amd.com (fix sysfs file path) Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> 
There are some performance issues being identified by dynamic EPP
and we don't want to have distributions turning it on by default
exposing them to users at this time.

Drop the kconfig option, and require an explicit opt in from kernel
command line or runtime sysfs option to turn it on.

Reported-by: Viktor Jägersküpper <viktor_jaegerskuepper@freenet.de>
Closes: https://lore.kernel.org/linux-pm/14a87c99-785c-4b16-bfce-35ecbf053448@freenet.de/
Reported-by: Stuart Meckle <stuartmeckle@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221473
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260512221947.1652988-1-mario.limonciello@amd.com
(fix sysfs file path)
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
cpufreq: intel_pstate: Use HYBRID_SCALING_FACTOR_ADL for Bartlett Lake 2026-05-13T19:44:44+00:00 Henry Tseng henrytseng@qnap.com 2026-05-13T10:28:46+00:00 85cffdb21bc1a928f4c89f88dcdf42a460b04e70 Bartlett Lake P-core only SKUs (e.g. Intel Core 9 273PE) do not report X86_FEATURE_HYBRID_CPU and are not in intel_hybrid_scaling_factor[]. In hwp_get_cpu_scaling(), the non-hybrid fallback then applies core_get_scaling() (100000), producing cpuinfo_max_freq values that exceed the documented Max Turbo Frequency: intel_pstate: CPU0: PERF_CTL turbo = 57 intel_pstate: CPU0: HWP_CAP guaranteed = 30 intel_pstate: CPU0: HWP_CAP highest = 70 intel_pstate: CPU0: HWP-to-frequency scaling factor: 100000 intel_pstate: set_policy cpuinfo.max 7000000 policy->max 7000000 ... intel_pstate: CPU12: PERF_CTL turbo = 57 intel_pstate: CPU12: HWP_CAP guaranteed = 30 intel_pstate: CPU12: HWP_CAP highest = 73 intel_pstate: CPU12: HWP-to-frequency scaling factor: 100000 intel_pstate: set_policy cpuinfo.max 7300000 policy->max 7300000 ... Per the Intel datasheet [1], the Intel Core 9 273PE specifies: Performance-cores: 12 Efficient-cores: 0 Max Turbo Frequency: 5.7 GHz Intel Thermal Velocity Boost Frequency: 5.7 GHz Intel Turbo Boost Max Technology 3.0 Frequency: 5.6 GHz Performance-core Max Turbo Frequency: 5.4 GHz Performance-core Base Frequency: 2.3 GHz Bartlett Lake P-cores are Raptor Cove cores, per commit d466304c4322 ("x86/cpu: Add CPU model number for Bartlett Lake CPUs with Raptor Cove cores"). The Alder Lake and Raptor Lake P-core entries in intel_hybrid_scaling_factor[] use HYBRID_SCALING_FACTOR_ADL (78741). The same factor applies to Bartlett Lake. Add Bartlett Lake to intel_hybrid_scaling_factor[] with HYBRID_SCALING_FACTOR_ADL so HWP performance levels map to the correct CPU frequencies matching the datasheet's Max Turbo Frequency. Link: https://www.intel.com/content/www/us/en/products/sku/245717/intel-core-9-processor-273pe-36m-cache-up-to-5-70-ghz/specifications.html [1] Signed-off-by: Henry Tseng <henrytseng@qnap.com> [ rjw: Changelog tweak ] Link: https://patch.msgid.link/20260513102847.75179-1-henrytseng@qnap.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Bartlett Lake P-core only SKUs (e.g. Intel Core 9 273PE)
do not report X86_FEATURE_HYBRID_CPU and are not in
intel_hybrid_scaling_factor[].  In hwp_get_cpu_scaling(), the
non-hybrid fallback then applies core_get_scaling() (100000),
producing cpuinfo_max_freq values that exceed the documented Max
Turbo Frequency:

  intel_pstate: CPU0: PERF_CTL turbo = 57
  intel_pstate: CPU0: HWP_CAP guaranteed = 30
  intel_pstate: CPU0: HWP_CAP highest = 70
  intel_pstate: CPU0: HWP-to-frequency scaling factor: 100000
  intel_pstate: set_policy cpuinfo.max 7000000 policy->max 7000000
  ...
  intel_pstate: CPU12: PERF_CTL turbo = 57
  intel_pstate: CPU12: HWP_CAP guaranteed = 30
  intel_pstate: CPU12: HWP_CAP highest = 73
  intel_pstate: CPU12: HWP-to-frequency scaling factor: 100000
  intel_pstate: set_policy cpuinfo.max 7300000 policy->max 7300000
  ...

Per the Intel datasheet [1], the Intel Core 9 273PE specifies:

  Performance-cores:                                 12
  Efficient-cores:                                   0
  Max Turbo Frequency:                               5.7 GHz
  Intel Thermal Velocity Boost Frequency:            5.7 GHz
  Intel Turbo Boost Max Technology 3.0 Frequency:    5.6 GHz
  Performance-core Max Turbo Frequency:              5.4 GHz
  Performance-core Base Frequency:                   2.3 GHz

Bartlett Lake P-cores are Raptor Cove cores, per
commit d466304c4322 ("x86/cpu: Add CPU model number for Bartlett
Lake CPUs with Raptor Cove cores").  The Alder Lake and Raptor Lake
P-core entries in intel_hybrid_scaling_factor[] use
HYBRID_SCALING_FACTOR_ADL (78741).  The same factor applies to
Bartlett Lake.

Add Bartlett Lake to intel_hybrid_scaling_factor[] with
HYBRID_SCALING_FACTOR_ADL so HWP performance levels map to the
correct CPU frequencies matching the datasheet's Max Turbo Frequency.

Link: https://www.intel.com/content/www/us/en/products/sku/245717/intel-core-9-processor-273pe-36m-cache-up-to-5-70-ghz/specifications.html [1]
Signed-off-by: Henry Tseng <henrytseng@qnap.com>
[ rjw: Changelog tweak ]
Link: https://patch.msgid.link/20260513102847.75179-1-henrytseng@qnap.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: intel_pstate: Use correct scaling factor on Raptor Lake-E 2026-05-13T19:42:07+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2026-05-12T19:20:30+00:00 0e7c710478b3089cdfe8669347f77b163e836c4f Raptor Lake-E has the same processor ID as Raptor Lake-S, so there is an entry in intel_hybrid_scaling_factor[] for it. It does not contain E-cores though and hybrid_get_cpu_type() returns 0 for its P-cores, so they get the default "core" scaling factor. However, the original Raptor Lake scaling factor for P-cores still needs to be used for mapping the HWP performance levels of the P-cores in Raptor Lake-E to frequency, as though they were part of a real hybrid system. To address this, update hwp_get_cpu_scaling() to return hybrid_scaling_factor, which is the P-core scaling factor retrieved from intel_hybrid_scaling_factor[], for all CPUs that are not enumerated as E-cores. Fixes: 9b18d536b124 ("cpufreq: intel_pstate: Use CPPC to get scaling factors") Link: https://lore.kernel.org/all/20260511235328.2018458-1-srinivas.pandruvada@linux.intel.com/ Reported-by: Henry Tseng <henrytseng@qnap.com> Closes: https://lore.kernel.org/linux-pm/20260508063032.3248602-1-henrytseng@qnap.com/ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: All applicable <stable@vger.kernel.org> Link: https://patch.msgid.link/4523296.ejJDZkT8p0@rafael.j.wysocki 
Raptor Lake-E has the same processor ID as Raptor Lake-S, so there is
an entry in intel_hybrid_scaling_factor[] for it.  It does not contain
E-cores though and hybrid_get_cpu_type() returns 0 for its P-cores, so
they get the default "core" scaling factor.  However, the original
Raptor Lake scaling factor for P-cores still needs to be used for
mapping the HWP performance levels of the P-cores in Raptor Lake-E to
frequency, as though they were part of a real hybrid system.

To address this, update hwp_get_cpu_scaling() to return
hybrid_scaling_factor, which is the P-core scaling factor
retrieved from intel_hybrid_scaling_factor[], for all CPUs
that are not enumerated as E-cores.

Fixes: 9b18d536b124 ("cpufreq: intel_pstate: Use CPPC to get scaling factors")
Link: https://lore.kernel.org/all/20260511235328.2018458-1-srinivas.pandruvada@linux.intel.com/
Reported-by: Henry Tseng <henrytseng@qnap.com>
Closes: https://lore.kernel.org/linux-pm/20260508063032.3248602-1-henrytseng@qnap.com/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: All applicable <stable@vger.kernel.org>
Link: https://patch.msgid.link/4523296.ejJDZkT8p0@rafael.j.wysocki
cpufreq/amd-pstate-ut: Drop policy reference before driver switch 2026-05-08T05:30:50+00:00 K Prateek Nayak kprateek.nayak@amd.com 2026-05-08T05:17:48+00:00 f9f16835d4dc46113c0a72625ffbf61f1aa95e5c Recent changes to the EPP unit test tries to perform a driver switch with a cpufreq_policy reference held when the driver is loaded into anything but the active mode which leads to a circular dependency and the unit test hanging indefinitely. Drop the reference before driver switch and grab it back once the driver mode is stabilized for the test. The EPP writes are only possible with CPUFREQ_POLICY_POWERSAVE policy. Temporarily switch the cpudata->policy (while holding the write end of the policy->rwsem) to CPUFREQ_POLICY_POWERSAVE and restore the original policy once tests are done. To ensure the final EPP is correct in case the driver started with CPUFREQ_POLICY_PERFORMANCE, EPP performance is tested last. The __free() based cleanup for cpufreq_policy is lost in the process. Reported-by: Kalpana Shetty <kalpana.shetty@amd.com> Fixes: 7e173bc310d2b ("cpufreq/amd-pstate-ut: Add a unit test for raw EPP") Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20260508051748.10484-7-kprateek.nayak@amd.com Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> 
Recent changes to the EPP unit test tries to perform a driver switch
with a cpufreq_policy reference held when the driver is loaded into
anything but the active mode which leads to a circular dependency and
the unit test hanging indefinitely.

Drop the reference before driver switch and grab it back once the driver
mode is stabilized for the test.

The EPP writes are only possible with CPUFREQ_POLICY_POWERSAVE policy.
Temporarily switch the cpudata->policy (while holding the write end of
the policy->rwsem) to CPUFREQ_POLICY_POWERSAVE and restore the original
policy once tests are done. To ensure the final EPP is correct in case
the driver started with CPUFREQ_POLICY_PERFORMANCE, EPP performance is
tested last.

The __free() based cleanup for cpufreq_policy is lost in the process.

Reported-by: Kalpana Shetty <kalpana.shetty@amd.com>
Fixes: 7e173bc310d2b ("cpufreq/amd-pstate-ut: Add a unit test for raw EPP")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260508051748.10484-7-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
cpufreq/amd-pstate: Use "epp_default_dc" as default when dynamic_epp is disabled 2026-05-08T05:30:50+00:00 K Prateek Nayak kprateek.nayak@amd.com 2026-05-08T05:17:47+00:00 caa822d312be54e3fe1a3b52c887e0888e149c12 If "dynamic_epp" is disabled, the driver initialization and the default EPP selection from sysfs currently sets the EPP based on the power supply state of the system at that time but there is no power supply callbacks registered to toggle it when the power supply state changes. This can lead to faster battery drain on platforms that start off while being plugged to the wall but later move to battery power since the EPP stays at AMD_CPPC_EPP_PERFORMANCE. Use "epp_default_dc" as the default EPP selection when dynamic_epp is disabled, restoring older behavior. On servers, this defaults to AMD_CPPC_EPP_PERFORMANCE and on other platforms, it defaults to AMD_CPPC_EPP_BALANCE_PERFORMANCE. Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference") Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20260508051748.10484-6-kprateek.nayak@amd.com Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> 
If "dynamic_epp" is disabled, the driver initialization and the default
EPP selection from sysfs currently sets the EPP based on the power
supply state of the system at that time but there is no power supply
callbacks registered to toggle it when the power supply state changes.

This can lead to faster battery drain on platforms that start off while
being plugged to the wall but later move to battery power since the EPP
stays at AMD_CPPC_EPP_PERFORMANCE.

Use "epp_default_dc" as the default EPP selection when dynamic_epp is
disabled, restoring older behavior. On servers, this defaults to
AMD_CPPC_EPP_PERFORMANCE and on other platforms, it defaults to
AMD_CPPC_EPP_BALANCE_PERFORMANCE.

Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260508051748.10484-6-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
cpufreq/amd-pstate: Reorder notifier unregistration and floor perf reset 2026-05-08T05:30:50+00:00 K Prateek Nayak kprateek.nayak@amd.com 2026-05-08T05:17:46+00:00 f3acf7ff113007557538b278ccb0e4ab7ae513ea An active power supply notifier can race with amd_pstate_epp_cpu_exit() trying to reset the floor perf and can overwrite the floor perf set in MSR_AMD_CPPC_REQ. Unregister the notifier before setting the floor perf to prevent the rare race. Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference") Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20260508051748.10484-5-kprateek.nayak@amd.com Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> 
An active power supply notifier can race with amd_pstate_epp_cpu_exit()
trying to reset the floor perf and can overwrite the floor perf set in
MSR_AMD_CPPC_REQ.

Unregister the notifier before setting the floor perf to prevent the
rare race.

Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260508051748.10484-5-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
cpufreq/amd-pstate: Allow writes to dynamic_epp when state isn't modified 2026-05-08T05:30:50+00:00 K Prateek Nayak kprateek.nayak@amd.com 2026-05-08T05:17:45+00:00 c5eed6ddc757e477f52b3d99bfde9e59975c72ca Writing the current "dynamic_epp" state to sysfs fails with -EINVAL even though the desired result was achieved. Allow writes to "dynamic_epp" that does not modify the state. Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference") Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20260508051748.10484-4-kprateek.nayak@amd.com Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> 
Writing the current "dynamic_epp" state to sysfs fails with -EINVAL even
though the desired result was achieved. Allow writes to "dynamic_epp"
that does not modify the state.

Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260508051748.10484-4-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
cpufreq/amd-pstate: Return -ENOMEM on failure to allocate profile_name 2026-05-08T05:30:50+00:00 K Prateek Nayak kprateek.nayak@amd.com 2026-05-08T05:17:44+00:00 87d2a8dec0f02b200eb3527da0ab11ba4d4e7deb Failure to allocate profile name will return -EINVAL from platform_profile_register() while in fact, it is a failure to allocate memory for the profile_name string. Return -ENOMEM when kasprintf() fails to allocate profile_name string. Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference") Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20260508051748.10484-3-kprateek.nayak@amd.com Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> 
Failure to allocate profile name will return -EINVAL from
platform_profile_register() while in fact, it is a failure to allocate
memory for the profile_name string.

Return -ENOMEM when kasprintf() fails to allocate profile_name string.

Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260508051748.10484-3-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
cpufreq/amd-pstate: Grab "amd_pstate_driver_lock" when toggling dynamic_epp 2026-05-08T05:30:50+00:00 K Prateek Nayak kprateek.nayak@amd.com 2026-05-08T05:17:43+00:00 9228169d2ae055ed09a163887fc59a710a5eb73b Concurrently changing driver mode and dynamic_epp with: echo passive > /sys/devices/system/cpu/amd_pstate/status& echo disable > /sys/devices/system/cpu/amd_pstate/dynamic_epp& hits the WARN_ON_ONCE() in static_key_disable_cpuslocked() and hangs the system since both sysfs writes are trying to do amd_pstate_change_driver_mode() without any synchronization. Grab the "amd_pstate_driver_lock" mutex when modifying "dynamic_epp" to prevent the two paths from racing with each other. Add a lockdep assertion for "amd_pstate_driver_lock" in amd_pstate_change_driver_mode() to formalize the dependency. Since "cppc_mode" is stable under "amd_pstate_driver_lock", only reload the driver when in "AMD_PSTATE_ACTIVE" mode and reject all writes when in passive or guided mode, or if the driver is not loaded, since only active mode operates on EPP. Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference") Reviewed-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20260508051748.10484-2-kprateek.nayak@amd.com Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org> 
Concurrently changing driver mode and dynamic_epp with:

    echo passive > /sys/devices/system/cpu/amd_pstate/status&
    echo disable > /sys/devices/system/cpu/amd_pstate/dynamic_epp&

hits the WARN_ON_ONCE() in static_key_disable_cpuslocked() and hangs the
system since both sysfs writes are trying to do
amd_pstate_change_driver_mode() without any synchronization.

Grab the "amd_pstate_driver_lock" mutex when modifying "dynamic_epp" to
prevent the two paths from racing with each other. Add a lockdep
assertion for "amd_pstate_driver_lock" in
amd_pstate_change_driver_mode() to formalize the dependency.

Since "cppc_mode" is stable under "amd_pstate_driver_lock", only reload
the driver when in "AMD_PSTATE_ACTIVE" mode and reject all writes when
in passive or guided mode, or if the driver is not loaded, since only
active mode operates on EPP.

Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260508051748.10484-2-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>