On Tue, Nov 29, 2016 at 6:42 AM, Viresh Kumar viresh.kumar@linaro.org wrote:
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.
In order to fix that up properly, we need to revisit APIs like dev_pm_opp_set_regulator() and make them talk in terms of cookies provided by the OPP core. But such a solution will be hard to backport to stable kernels.
This patch attempts to fix this problem (in a Hacky way) by specially handling the first cpu in the mask. A FIXME is also added to make sure that this Hack doesn't get unnoticed later on.
Cc: # v4.4+ stable@vger.kernel.org Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
V2->V3:
- Fix $Subject, which carried text from V1.
V1->V2:
- A completely different approach, more of hack so that backport to stable kernels can be done easily.
- A more comprehensive solution is required to fix the design flaws.
I'll wait for a response from Stephen this time.
Thanks, Rafael