Messages in this thread Patch in this message | | | From | Kyle Meyer <> | Subject | [PATCH] acpi-cpufreq: Skip initialization if a cpufreq driver exists | Date | Fri, 21 May 2021 17:19:06 -0500 |
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Revert part of commit 75c0758137c7a ("acpi-cpufreq: Fail initialization if driver cannot be registered").
acpi-cpufreq is mutually exclusive with intel_pstate, however, acpi-cpufreq is loaded multiple times during startup while intel_pstate is enabled. On systems using systemd the kernel triggers one uevent for each device as a result of systemd-udev-trigger.service. The service exists to retrigger all devices as uevents sent by the kernel before systemd-udevd is running are missed. The delay caused by systemd-udevd repeatedly loading the driver, getting a fail return, and unloading the driver twice per logical CPU has a significant impact on the startup time, and can cause some devices to be unavailable after reaching the root login prompt.
Load the driver once but skip initialization if a cpufreq driver exists by changing the return value of cpufreq_get_current_driver() from -EEXIST to 0.
Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com> --- drivers/cpufreq/acpi-cpufreq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c index 7e7450453714..e79a945369d1 100644 --- a/drivers/cpufreq/acpi-cpufreq.c +++ b/drivers/cpufreq/acpi-cpufreq.c @@ -1003,7 +1003,7 @@ static int __init acpi_cpufreq_init(void) /* don't keep reloading if cpufreq_driver exists */ if (cpufreq_get_current_driver()) - return -EEXIST; + return 0; pr_debug("%s\n", __func__); -- 2.26.2
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