Hi Doug, Am Donnerstag, 18. August 2016, 11:56:01 CEST schrieb Douglas Anderson: > On rk3288 it was important that powerdown and powerup counts for the > CPU/GPU in the kernel because: somehow this sentence seems to miss some verb or so :-) > * The power on default was crazy long. > * We couldn't rely on the firmware to set this up because really this > wasn't the firmware's job--the kernel was the only one that really > cared about bringing up / down CPUs and the GPU and doing suspend / > resume (which involves bringing up / down CPUs). > > On newer ARM systems (like rk3399) ARM Trusted Firmware is in charge of > bringing up and down the CPUs and it really should be in charge of > setting all these counts right. After all ATF is in charge of suspend / > resume and CPU up / down. Let's get out of the way and let ATF do its > job. > > A few other motivations for doing this: > * Depending on another configuration (PMU_24M_EN_CFG) these counts can > be either in 24M or 32k cycles. Thus, though ATF isn't really so > involved in bringing up the GPU, ATF should probably manage the counts > for everything so it can also manage the 24M / 32k choice. > * It turns out that (right now) 24M mode is broken on rk3399 and not > being used. That means that the count the kernel was programming > in (24) was not 1 us (which it seems was intended) but was actually > .75 ms > * On rk3399 there are actually 2 separate registers for setting CPU > up/down time plus 1 register for GPU up/down time. The curent kernel > code actually was putting the register for the "little" cores in the > "CPU" slot and the register for the "big" cores in the "GPU" slot. It > was never initting the GPU counts. > > Note: this change assumes that ATF will actually set these values at > boot, as I'm proposing in <http://crosreview.com/372381>. I'd hope to see a link to an ATF github pull request here :-) But I guess that simply needs some more discussion on your side. > Signed-off-by: Douglas Anderson <dianders at chromium.org> change itself looks good to me. So I guess we'll just need to wait for the counterpart to land in the ATF or do you know if the poweron-defaults are somewhat sane? Heiko
