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Date:   Thu, 23 Apr 2020 22:37:35 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Philipp Rossak <embed3d@gmail.com>
Cc:     "H. Nikolaus Schaller" <hns@goldelico.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        =?utf-8?Q?Beno=C3=AEt?= Cousson <bcousson@baylibre.com>,
        Tony Lindgren <tony@atomide.com>,
        Paul Cercueil <paul@crapouillou.net>,
        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paulburton@kernel.org>,
        James Hogan <jhogan@kernel.org>, Kukjin Kim <kgene@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Chen-Yu Tsai <wens@csie.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
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Subject: Re: [PATCH v6 00/12] ARM/MIPS: DTS: add child nodes describing the
 PVRSGX GPU present in some OMAP SoC and JZ4780 (and many more)
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On Tue, Apr 21, 2020 at 06:42:17PM +0200, Philipp Rossak wrote:
> Hi,
>=20
> On 21.04.20 13:21, Maxime Ripard wrote:
> > Hi,
> >=20
> > On Tue, Apr 21, 2020 at 11:57:33AM +0200, Philipp Rossak wrote:
> > > On 20.04.20 09:38, Maxime Ripard wrote:
> > > > Hi,
> > > >=20
> > > > On Fri, Apr 17, 2020 at 02:09:06PM +0200, Philipp Rossak wrote:
> > > > > > > I'm a bit skeptical on that one since it doesn't even list the
> > > > > > > interrupts connected to the GPU that the binding mandates.
> > > > > >=20
> > > > > > I think he left it out for a future update.
> > > > > > But best he comments himself.
> > > > >=20
> > > > > I'm currently working on those bindings. They are now 90% done, b=
ut they are
> > > > > not finished till now. Currently there is some mainline support m=
issing to
> > > > > add the full binding. The A83T and also the A31/A31s have a GPU P=
ower Off
> > > > > Gating Register in the R_PRCM module, that is not supported right=
 now in
> > > > > Mainline. The Register need to be written when the GPU is powered=
 on and
> > > > > off.
> > > > >=20
> > > > > @Maxime: I totally agree on your point that a demo needs to be pr=
ovided
> > > > > before the related DTS patches should be provided. That's the rea=
son why I
> > > > > added the gpu placeholder patches.
> > > > > Do you have an idea how a driver for the R_PRCM stuff can look li=
ke? I'm not
> > > > > that experienced with the clock driver framework.
> > > >=20
> > > > It looks like a power-domain to me, so you'd rather plug that into =
the genpd
> > > > framework.
> > >=20
> > > I had a look on genpd and I'm not really sure if that fits.
> > >=20
> > > It is basically some bit that verify that the clocks should be enable=
d or
> > > disabled.
> >=20
> > No, it can do much more than that. It's a framework to control the SoCs=
 power
> > domains, so clocks might be a part of it, but most of the time it's goi=
ng to be
> > about powering up a particular device.
> >=20
> So I think I've found now the right piece of documentation and a driver t=
hat
> implements something similar [1].
>=20
> So I will write a similar driver like linked above that only sets the rig=
ht
> bits for A83T and A31/A31s.
> Do you think this is the right approach?

That sounds about right yes

Maxime

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