Messages in this thread | | | Subject | Re: [PATCH v2 0/9] Exynos Adaptive Supply Voltage support | From | Sylwester Nawrocki <> | Date | Tue, 20 Aug 2019 11:03:09 +0200 |
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On 8/20/19 05:01, Viresh Kumar wrote: > On 19-08-19, 15:39, Sylwester Nawrocki wrote: >> Unfortunately not, the patch set as I see it is another way of updating >> an OPP after it was parsed from DT. OPP remove/add could work equally >> well in our use case. > > Adding OPPs dynamically has limitations, you can't set many values which are > otherwise possible with DT. And removing/adding is not the right thing to do > technically.
Thanks for explanation, I was not aware of that.
>> The problem is that we have the information on how to translate the >> common OPP voltage to a voltage specific to given silicon encoded jointly >> in the ASV tables and the CHIPID registers (efuse/OTP memory). >> Additionally, algorithm of selecting ASV data (OPP voltage) based on >> the "key" data from registers is not generic, it is usually different >> per each SoC type. >> >> I tried to identify some patterns in those tables in order to simplify >> possible DT binding, but that was not really successful. I ended up just >> keeping whole tables. > > Sorry but I am unable to understand the difficulty you are facing now. So what I > suggest is something like this.
The difficulty was about representing data from tables asv_{arm,kfc}_table[][] added in patch 3/9 of the series in devicetree. If you have no objections about keeping those tables in the driver then I can't see any difficulties. > - Use DT to get a frequency and voltage for each frequency.
Yes, this is what happens now, we have common OPPs in DT that work for each SoC revision.
> - At runtime, based on SoC, registers, efuses, etc, update the voltage of the > OPPs. > - This algo can be different for each SoC, no one is stopping you from doing > that. > > Am I missing something ?
Not really, this is basically what happens in the $subject patch series.
Then IIUC what I would need to change is to modify exynos_asv_update_cpu_opps() function in patch 3/9 to use dev_pm_opp_adjust_voltage() rather than dev_pm_opp_remove(), dev_pm_opp_add().
-- Thanks, Sylwester
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