armhf: cpufreq doesn't autoload by default
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Fix Released
|
Undecided
|
Paolo Pisati | ||
Utopic |
Fix Released
|
Undecided
|
Unassigned | ||
Vivid |
Fix Released
|
Undecided
|
Unassigned |
Bug Description
SRU Justification:
Impact: upon boot, frequency scaling is not working.
Fix: Apply the patches, recompile and reboot.
Testcase: Try booting a beaglebone with and without a patched kernel.
With this series applied there should be:
ubuntu@
total 0
drwxr-xr-x 3 root root 0 May 22 07:03 .
drwxr-xr-x 5 root root 0 May 22 07:03 ..
-r--r--r-- 1 root root 4096 May 22 07:03 affected_cpus
-r-------- 1 root root 4096 May 22 07:03 cpuinfo_cur_freq
-r--r--r-- 1 root root 4096 May 22 07:03 cpuinfo_max_freq
-r--r--r-- 1 root root 4096 May 22 07:03 cpuinfo_min_freq
-r--r--r-- 1 root root 4096 May 22 07:03 cpuinfo_
-r--r--r-- 1 root root 4096 May 22 07:03 related_cpus
-r--r--r-- 1 root root 4096 May 22 07:03 scaling_
-r--r--r-- 1 root root 4096 May 22 07:03 scaling_
-r--r--r-- 1 root root 4096 May 22 07:03 scaling_cur_freq
-r--r--r-- 1 root root 4096 May 22 07:03 scaling_driver
-rw-r--r-- 1 root root 4096 May 22 04:43 scaling_governor
-rw-r--r-- 1 root root 4096 May 22 07:03 scaling_max_freq
-rw-r--r-- 1 root root 4096 May 22 07:03 scaling_min_freq
-rw-r--r-- 1 root root 4096 May 22 07:03 scaling_setspeed
drwxr-xr-x 2 root root 0 May 22 07:03 stats
ubuntu@
With an unpatched kernel, until the cpufreq module is loaded, that directory doesn't exist.
...
While cpufreq support on armhf is available for a while, if support is compiled as a kernel module, the corresponding module doesn't autoload by default, and thus frequency scaling is not active upon boot until a user manually load it (or until /etc/modules is modified to forcibly load it).
While in Trusty cpufreq was built-in on armhf, starting with Utopic we made support available as a kernel module, making people think that cpufreq was either broken or missing in their new kernels.
To fix it, revert back that decision and make cpufreq compiled-in again on armhf - it affects Utopic and Vivid kernels.
tags: | added: patch |
description: | updated |
Changed in linux (Ubuntu): | |
assignee: | nobody → Paolo Pisati (p-pisati) |
Changed in linux (Ubuntu Utopic): | |
status: | New → Fix Committed |
Changed in linux (Ubuntu Vivid): | |
status: | New → Fix Committed |
Changed in linux (Ubuntu): | |
status: | Incomplete → Fix Committed |
tags: |
added: verification-done-utopic removed: verification-needed-utopic |
tags: |
added: verification-done-vivid removed: verification-needed-vivid |
This patch is for Utopic.