On Fri, Nov 25, 2016 at 7:55 AM, Viresh Kumar [off-list ref] wrote:

On 25-11-16, 12:23, Viresh Kumar wrote:

quoted

Joonyoung Shim reported an interesting problem on his ARM octa-core
Odoroid-XU3 platform. During system suspend, dev_pm_opp_put_regulator()
was failing for a struct device for which dev_pm_opp_set_regulator() is
called earlier.

This happened because an earlier call to
dev_pm_opp_of_cpumask_remove_table() function (from cpufreq-dt.c file)
removed all the entries from opp_table->dev_list apart from the last CPU
device in the cpumask of CPUs sharing the OPP.

But both dev_pm_opp_set_regulator() and dev_pm_opp_put_regulator()
routines get CPU device for the first CPU in the cpumask. And so the OPP
core failed to find the OPP table for the struct device.

This patch attempts to fix this problem by adding another field in the
struct opp_device: inactive.

Instead of removing the entries from the list during
dev_pm_opp_of_cpumask_remove_table() function call, we mark them as
inactive. Such inactive devices will not be used by the core in most of
the cases, like before, but will be used only at special places which
need to take inactive devices into account.

All the devices are removed from the list together now and that happens
only when the opp_table gets destroyed.

This patch is tested on Dual A15, Exynos5250 platform by compiling the
cpufreq-dt driver as a module. The module is inserted/removed multiple
times with combinations of CPU offline/online steps.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

@Rafael: Can you please add following while applying the patch ?

Cc: <redacted> # v4.4+

Yes, I can, but I need an ACK for this from Stephen too.

Thanks,
Rafael