Hi,
Meelis Roos reported hangs during boot in the longhaul cpufreq driver, after
commit 12478cf0c55 (cpufreq: Make sure frequency transitions are serialized).
The root-cause of this issue is the extra invocation of the
cpufreq_freq_transition_begin() and cpufreq_freq_transition_end() APIs in the
longhaul driver. I found similar issues in the powernow-k6 and powernow-k7
drivers as well. This patchset fixes the issue in all the 3 drivers and also
adds a debug infrastructure to catch such issues easily.
Patches 1-4 fix the regression in longhaul, powernow-k6 and powernow-k7
drivers. (Patch 2 fixes a different bug in powernow-k6, and it is kept as a
separate patch instead of merging it with patch 3, because I felt that it was
a bit subtle and needed attention in a separate patch).
Patch 5 adds a debug infrastructure to the cpufreq core to catch such problems
more easily in the future.
Changes in v2:
--------------
* Modified patch 1 to take error returns into account, as pointed out by
Viresh.
* Added patch 2 to fix the existing issue in the powernow-k6 driver, pointed
out by Viresh.
* Added patch 5 to introduce a debug infrastructure to catch such issues
easily.
Srivatsa S. Bhat (5):
cpufreq, longhaul: Fix double invocation of cpufreq_freq_transition_begin/end
cpufreq, powernow-k6: Fix incorrect comparison with max_multipler
cpufreq, powernow-k6: Fix double invocation of cpufreq_freq_transition_begin/end
cpufreq, powernow-k7: Fix double invocation of cpufreq_freq_transition_begin/end
cpufreq: Catch double invocations of cpufreq_freq_transition_begin/end
drivers/cpufreq/cpufreq.c | 12 ++++++++++++
drivers/cpufreq/longhaul.c | 36 ++++++++++++++++++++++++------------
drivers/cpufreq/powernow-k6.c | 23 +++++++++++++----------
drivers/cpufreq/powernow-k7.c | 4 ----
include/linux/cpufreq.h | 1 +
5 files changed, 50 insertions(+), 26 deletions(-)
Thanks,
Srivatsa S. Bhat
IBM Linux Technology Center
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