cpufreq/amd-pstate: Add support for the "Requested CPU Min frequency" BIOS option

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Initialize lower frequency limit to the "Requested CPU Min frequency"
BIOS option (if it is set) value as part of the driver->init()
callback. The BIOS specified value is passed by the PMFW as min_perf in
CPPC_REQ MSR. To ensure that we don't mistake a stale min_perf value in
CPPC_REQ value as the "Requested CPU Min frequency" during a kexec wakeup,
reset the CPPC_REQ.min_perf value back to the BIOS specified one in the
offline, exit and suspend callbacks.

amd_pstate_target() and amd_pstate_epp_update_limit() which are invoked
as part of the resume() and online() callbacks will take care of restoring
the CPPC_REQ back to the correct values.

Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20250428071623.4309-1-dhananjay.ugwekar@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

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Dhananjay Ugwekar 2025-04-28 07:16:24 +00:00 • committed by Mario Limonciello

parent 98b52c6b0b

commit 608a76b652

2 changed files with 71 additions and 13 deletions

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82

drivers/cpufreq/amd-pstate.c

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2

drivers/cpufreq/amd-pstate.h

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