Re: [PATCH] soc: rockchip: power-domain: Don't (incorrectly) set rk3399 up/down counts

From: Heiko Stuebner
Date: Thu Aug 18 2016 - 21:53:25 EST


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@xxxxxxxxx> 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@xxxxxxxxxxxx>
> >
> > 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