CPR (Core Power Reduction)


#1

What is the current status of CPR / voltage scaling on 820/Linux? I understand that this driver has not been implemented yet in the Linaro kernel, is it on the roadmap?

We think that the thermal performance of the Linaro Linux kernel is different vs earlier Android kernels.


#2

Kind of. There is a bit of working going on behind the scenes that might help fix the instabilities the naive implementations suffered from but there is nothing specific and no predicted dates (other than “likely to be a long wait”).


#3

Hi @althea:

I was looking at patches related to another issue (Boot failure / crash during the boot?) and the second patch (https://patchwork.kernel.org/patch/10377933/) would certainly improve the thermal performance at peak speeds.

Without the voltage scaling based on the fuses of each individual chip you are going to see different thermal throttling on each individual chip. The voltage scaling based on the fuses on the individual chip will make every physical copy of a particular system close to the same performance. At lower CPU speeds this won’t make much difference.

If you are interested, I can explain Why this would affect peak performance and thermals.

-Lawrence-
No longer a Qualcomm employee
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