On Tue, 2015-07-28 at 15:45 +0530, Amit Pundir wrote:
Hi Tixy,
On 27 July 2015 at 23:34, Jon Medhurst (Tixy) tixy@linaro.org wrote:
Hi
With an ARM Landing Team branch based on LSK 3.18 Android I'm seeing a hang if I
echo 0 > /sys/devices/system/cpu/cpu1/online
After bisecting, I fixed this problem by reverting commit 553b785b5383 ("cpufreq: Iterate over all the possible cpus to create powerstats.")
So in this patch I believe instead of "for_each_possible_cpu" we should use "for_each_online_cpu". Can you please re-enable this patch and try this change?
That gets rid of the hang, but it somewhat defeats the purpose of the original patch doesn't it? Though that patch itself looks a bit suspect as the module init function already calls cpufreq_powerstats_create for each online cpu (via cpufreq_stats_create_table).
Anyway, I don't fancy opening this can of worms further. Google seems to have lots of patches in this area and as even the upstream maintainers seem to struggle to catch all the interactions within cpufreq I generally don't trust any cpufreq patches ;-)
BTW, the hang was that serial console stops responding after the cpu is offlined. This is on Juno with an Open Embedded files system, no GUI (well, framebuffer text console).