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author | Prashant Malani <pmalani@google.com> | 2025-07-22 05:55:40 +0000 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2025-07-22 12:13:12 +0200 |
commit | 0a1416a49e63c320f6e6c1c8d07e1b58c0d4a3f3 (patch) | |
tree | a0d49536d90e3751382fe2c3f6f82a2c0d4cd717 /drivers/cdx/controller/cdx_controller.c | |
parent | ba0205042944b38a8b8ad462128072424b71c690 (diff) |
cpufreq: CPPC: Mark driver with NEED_UPDATE_LIMITS flag
AMU counters on certain CPPC-based platforms tend to yield inaccurate
delivered performance measurements on systems that are idle/mostly idle.
This results in an inaccurate frequency being stored by cpufreq in its
policy structure when the CPU is brought online. [1]
Consequently, if the userspace governor tries to set the frequency to a
new value, there is a possibility that it would be the erroneous value
stored earlier. In such a scenario, cpufreq would assume that the
requested frequency has already been set and return early, resulting in
the correct/new frequency request never making it to the hardware.
Since the operating frequency is liable to this sort of inconsistency,
mark the CPPC driver with CPUFREQ_NEED_UPDATE_LIMITS so that it is always
invoked when a target frequency update is requested.
Link: https://lore.kernel.org/linux-pm/20250619000925.415528-3-pmalani@google.com/ [1]
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Prashant Malani <pmalani@google.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://patch.msgid.link/20250722055611.130574-2-pmalani@google.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cdx/controller/cdx_controller.c')
0 files changed, 0 insertions, 0 deletions