Re: [PATCH v2 13/13] WIP: ARM: tegra: Add Tegra114 powergate support

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On Thu, 2013-10-17 at 03:12 +0800, Thierry Reding wrote:
> On Wed, Oct 16, 2013 at 10:31:11AM +0800, Joseph Lo wrote:
> > On Wed, 2013-10-16 at 05:50 +0800, Stephen Warren wrote:
> > > On 10/15/2013 09:28 AM, Thierry Reding wrote:
> > > > Extend the list of power gates found on Tegra114. Note that there are
> > > > now holes in the list, so perhaps a simple array is no longer the best
> > > > data structure to represent it. But perhaps this is good enough for now
> > > > and can be cleaned up in a follow up patch?
> > > 
> > > Peter should probably comment on this, since I think he's touched the
> > > powergate driver the most recently.
> > > 
> > > One idea might be to have the powergate IDs be "virtual", with a
> > > virtual->HW ID mapping table per SoC. The virtual IDs need not have any
> > > gaps. I'm not sure that having gaps is really much of a problem though,
> > > except for the debugfs code in powergate.c...
> > > 
> > > > diff --git a/include/linux/tegra-powergate.h b/include/linux/tegra-powergate.h
> > > 
> > > > +#define TEGRA_POWERGATE_DISA	18
> > > > +#define TEGRA_POWERGATE_DISB	19
> > > 
> > > s/DIS/DSI/ perhaps?
> > > 
> > > > -#define TEGRA_POWERGATE_CPU0	TEGRA_POWERGATE_CPU
> > > 
> > > I expect that was added deliberately. Perhaps Peter or Joseph can
> > > comment? Admittedly, it's not used right now.
> > > 
> > > BTW, while you're fiddling with powergate.c, I note that
> > > mach-tegra/pmc.c #defines some TEGRA_POWERGATE_xxx rather than including
> > > tegra-powergate.h. Can you fix that?
> > 
> > The reason why we didn't keep updated this code and use this driver is
> > because we want it to convert to use generic power domain
> > infrastructure[1]. Not sure this makes sense to you. (Only PCIe uses
> > this powergate driver until now.)
> 
> Hi Joseph,
> 
> Is this being tracked in an internal bug? Can you provide a bug number
> for me? Also do you know if anyone's actively working on this?

Yes, it was 1264196. And I am the owner ...

As you know, except PCIe and XUSB(after Tegra114), only graphic and
video driver needs this driver to do PM domain control. And the power
sequence is pretty complicated here. It cannot be done by just toggling
the power bit in PMC. The other power client or memory client even need
to be considered if there are in the same domain. So I just finished
very initial part of them. And waiting for other drier that really need
them to continue.

We can discuss further internally before we decide how to do it.

Thanks,
Joseph


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