]> git.ipfire.org Git - thirdparty/kernel/stable.git/commit
cpufreq: CPPC: Avoid using CPUFREQ_ETERNAL as transition delay
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>
Sat, 18 Oct 2025 16:40:55 +0000 (12:40 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 29 Oct 2025 13:04:30 +0000 (14:04 +0100)
commit857e4357ebf1c1c43554f41d89ba52aebc900b57
tree8c6d4a5694e5566b0238175483eafaf7918f5034
parent19b8fe5f40a06e156cb6d405ba20d9568de83c96
cpufreq: CPPC: Avoid using CPUFREQ_ETERNAL as transition delay

[ Upstream commit f965d111e68f4a993cc44d487d416e3d954eea11 ]

If cppc_get_transition_latency() returns CPUFREQ_ETERNAL to indicate a
failure to retrieve the transition latency value from the platform
firmware, the CPPC cpufreq driver will use that value (converted to
microseconds) as the policy transition delay, but it is way too large
for any practical use.

Address this by making the driver use the cpufreq's default
transition latency value (in microseconds) as the transition delay
if CPUFREQ_ETERNAL is returned by cppc_get_transition_latency().

Fixes: d4f3388afd48 ("cpufreq / CPPC: Set platform specific transition_delay_us")
Cc: 5.19+ <stable@vger.kernel.org> # 5.19
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Jie Zhan <zhanjie9@hisilicon.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Qais Yousef <qyousef@layalina.io>
[ added CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS definition to include/linux/cpufreq.h ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/cpufreq/cppc_cpufreq.c
include/linux/cpufreq.h