Messages in this thread | | | Date | Tue, 29 Nov 2016 09:25:31 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH] PM / OPP: Allow inactive opp_device to be present in dev list |
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On 28-11-16, 18:46, Stephen Boyd wrote: > That's a lot of lines for something that we want to backport to > stable kernels!
Hmm, I agree.
> The whole dev_list design seems fairly broken to me. Another > solution would be to iterate the cpumask in reverse, but there > doesn't seem to be a construct for that and adding one is > probably not worth the effort. > > Adding yet another member to the structure and doing accounting > in different places seems to be papering over the problem as > well. Now we want to have "inactive" devices in the list? That > seems like a problem for cpufreq to solve. It can decide to not > call OPP APIs when the cpu device isn't actually physically > removed if it wants to. > > It also exposes the OPP API's strong reliance on struct device > for everything. Really we shouldn't be storing device pointers in > the OPP core at all because we're not treating them like the > reference counted objects they are. The dev_list should go > probably go away and be replaced with some sort of counter. It > would also be nice if struct device had a pointer to the OPP > table(s) for a device so the lookup is direct.
If the struct device gets a pointer to the opp-table, then yes we can kill the dev-list completely. I will work on cleaning up OPP core a bit later on.
> BTW, _dev_pm_opp_remove_table() calls _find_opp_dev() twice, once > to find the opp_table for a device and then to find the > opp_device inside the table that was used to match up the table > in the first place. Madness! > > Anyway, rant over, how about handing out the opp table pointer to > the caller so they can pass it back in when they call the put > side? That should fix the same problem if I understand correctly.
Yes, that can be a solution for the time being.
> We should think about changing the API further so that callers > have to "get" the OPP table cookie for their device and then pass > that pointer to the dev_pm_*_set() APIs instead of passing a > struct device pointer. That would save lots of cycles searching > for something we already had.
Hmm, we need to do some cleanup soon I believe. Also note that we want to kill the RCU thing :)
> -static inline void dev_pm_opp_put_regulator(struct device *dev) {} > +static inline void dev_pm_opp_put_regulator(struct opp_table *opp_table) {}
We need to modify few more things as well. I will send a patch for that soon.
-- viresh
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