Re: [PATCH 0/3] Add support for Tegra Activity Monitor

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On 10/29/2014 11:50 PM, Tomeu Vizoso wrote:
Hello,

these patches implement support for setting the rate of the EMC clock based on
stats collected from the ACTMON, a piece of hw in the Tegra124 that counts
memory accesses (among others).

It depends on the following in-flight patches:

* MC driver: http://thread.gmane.org/gmane.linux.ports.tegra/19623
* EMC driver: http://thread.gmane.org/gmane.linux.ports.arm.kernel/365125
* CPUFreq driver: http://thread.gmane.org/gmane.linux.kernel/1812962

I have pushed a branch here for testing:

I am not too familiar with DVFS, but after going through this series it really seems to me that this could use devfreq. In its current form this driver mixes control and policy and lacks flexibility, preventing e.g. to switch to a performance or power-saving profile. Could you study the feasibility of using devfreq for this?

I also wonder if this driver could not be made more flexible generally speaking - right now it is hardcoded that you can only control EMC frequency with it. I can imagine that we could want to control several clocks using the same counter information, and that e.g. a notifier block might help with that. But let's keep that for later - whether to use devfreq or not seems to be the most important question for now.
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