Am Donnerstag, 18. August 2016, 15:08:12 CEST schrieb Doug Anderson: > Hi, > > On Thu, Aug 18, 2016 at 3:03 PM, Heiko Stuebner <heiko at sntech.de> wrote: > > 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 :-) > > Sigh. I guess I can't type. > > On rk3288 it was important that powerdown and powerup counts for the > > CPU/GPU be set in the kernel because: > >> * 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. > > Caesar is going to get confirmation that the patch is OK then I think > he'll work on the ATF pull request. Once done we can update the link > here? yep and I can then also update your sentence above :-) > >> 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? > > Power on defaults are crappy (750 ms to turn on/off a CPU), so > non-ideal. Probably best to wait for ATF to land. ok, so we'll wait. As I might miss it when the other side gets merged into the ATF, can you ping here once that is done please? Heiko
