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

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Date:   Fri, 19 Aug 2016 00:20:01 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Doug Anderson <dianders@...omium.org>
Cc:     "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        zhangqing <zhangqing@...k-chips.com>,
        Caesar Wang <wxt@...k-chips.com>,
        Xing Zheng <zhengxing@...k-chips.com>,
        Derek Basehore <dbasehore@...omium.org>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] soc: rockchip: power-domain: Don't (incorrectly) set rk3399 up/down counts

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@...ech.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@...omium.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