cpufreq: CPPC: Use transition_delay_us depending transition_latency
authorGeorge Cherian <george.cherian@cavium.com>
Fri, 23 Mar 2018 10:30:31 +0000 (03:30 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 24 Apr 2018 07:36:21 +0000 (09:36 +0200)
commitf1e90bf95e5503fcedaf59ac52cbdc013068eeb4
tree2b607f84ee9c4f68064bc7815b07030764540a72
parent9427a4aecf2330ba70dd59f194416de3e49042e2
cpufreq: CPPC: Use transition_delay_us depending transition_latency

commit 3d41386d556db9f720e00de3e11e45f39cb5071c upstream.

With commit e948bc8fbee0 (cpufreq: Cap the default transition delay
value to 10 ms)  the cpufreq was not honouring the delay passed via
ACPI (PCCT). Due to which on ARM based platforms using CPPC the
cpufreq governor tries to change the frequency of CPUs faster than
expected.

This leads to continuous error messages like the following.
" ACPI CPPC: PCC check channel failed. Status=0 "

Earlier (without above commit) the default transition delay was
taken form the value passed from PCCT. Use the same value provided
by PCCT to set the transition_delay_us.

Fixes: e948bc8fbee0 (cpufreq: Cap the default transition delay value to 10 ms)
Signed-off-by: George Cherian <george.cherian@cavium.com>
Cc: 4.14+ <stable@vger.kernel.org> # 4.14+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/cpufreq/cppc_cpufreq.c