lkml.org 
[lkml]   [2021]   [May]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] acpi-cpufreq: Skip initialization if a cpufreq driver exists
Date
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
\
 
 \ /
  Last update: 2021-05-22 00:21    [W:1.242 / U:0.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site