On Sun, Mar 15, 2015 at 8:28 PM, Leo Yan leo.yan@linaro.org wrote:
On Sat, Mar 14, 2015 at 09:09:05AM +0800, Haojian Zhuang wrote:
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There's no any relationship between PSCI and thermal/power management. The thermal driver works without any dependance on boot loader. cpufreq driver is depend on loading MCU.
Here need note one thing, now thermal driver is dependent on cpufreq driver to limit cpu frequency; the cpufreq driver is dependent on mcu image loading.
Good to see that you're using the cpufreq cooling device in the thermal framework now.
If we resolve mcu image loading issue, then cpufreq driver and theral driver can be easily enabled. So now the first priority is mcu image loading.
i will focus on mcu image loading in next 1~2 days, the more detailed info pls see another email thread for mcu image loading issue.
- i believe MCU loading isn't finished yet in ATF, this will cause power
management problems, and possible overheating - it is needed
Yes.
From ARM's power data, A53 cores's power efficiency is 0.13mw/MHz (28nm HPM), so that if we run only 4 core's @729MHz, the cpus will only consume: 729MHz * 0.13mw/MHz * 4 = 379mw; the CPU part will not introduce too much power.
A few weeks ago, when i debugged thermal driver, the thermal sensor also told the temperature is not very high, usually less than 30'c. Here have one thing need note: on my board, i just use ramdisk fs, so i think GPU/VPU also have been disabled as well.
So how about we firstly enable ATF + PSCI, but only boot up first 4 cores (maxcpus=4)? So that we can easily move forward to the solution of ATF + UEFI, and also it will not introduce overheating issue.
You could also cap the frequency on the cores i.e. don't add DT entries for OPPs above, say 600MHz, in the default image. That might allow you to enable all 8 cores w/o reaching overheating conditions while you fix various dependencies. You will need to measure this with all 8 cores enabled and loaded (and GPU too) before picking a value, though.