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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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From:   "H. Nikolaus Schaller" <hns@goldelico.com>
In-Reply-To: <20200422151328.2oyqz7gqkbunmd6o@gilmour.lan>
Date:   Wed, 22 Apr 2020 18:09:01 +0200
Cc:     Tony Lindgren <tony@atomide.com>,
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        Jonathan Bakker <xc-racer2@live.ca>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
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        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>,
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        <devicetree@vger.kernel.org>,
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        OpenPVRSGX Linux Driver Group <openpvrsgx-devgroup@letux.org>,
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To:     Maxime Ripard <maxime@cerno.tech>
Sender: linux-kernel-owner@vger.kernel.org
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Hi Maxime,

> Am 22.04.2020 um 17:13 schrieb Maxime Ripard <maxime@cerno.tech>:
>=20
> On Wed, Apr 22, 2020 at 09:10:57AM +0200, H. Nikolaus Schaller wrote:
>>> Am 22.04.2020 um 08:58 schrieb Maxime Ripard <maxime@cerno.tech>:
>>>>=20
>>>> It also allows to handle different number of clocks (A31 seems to
>>>> need 4, Samsung, A83 and JZ4780 one) without changing the sgx =
bindings
>>>> or making big lists of conditionals. This variance would be handled
>>>> outside the sgx core bindings and driver.
>>>=20
>>> I disagree. Every other GPU binding and driver is handling that just =
fine, and
>>> the SGX is not special in any case here.
>>=20
>> Can you please better explain this? With example or a description
>> or a proposal?
>=20
> I can't, I don't have any knowledge about this GPU.

Hm. Now I am fully puzzled.
You have no knowledge about this GPU but disagree with our proposal?
Is it just gut feeling?

Anyways, we need to find a solution. Together.

>=20
>> I simply do not have your experience with "every other GPU" as you =
have.
>> And I admit that I can't read from your statement what we should do
>> to bring this topic forward.
>>=20
>> So please make a proposal how it should be in your view.
>=20
> If you need some inspiration, I guess you could look at the mali and =
vivante
> bindings once you have an idea of what the GPU needs across the SoCs =
it's
> integrated in.

Well, I do not need inspiration, we need to come to an agreement about
img,pvrsgx.yaml and we need some maintainer to finally pick it up.

I wonder how we can come to this stage.

If I look at vivante,gc.yaml or arm,mali-utgard.yaml I don't
see big differences to what we propose and those I see seem to come
from technical differences between sgx, vivante, mali etc. So there
is no single scheme that fits all different gpu types.

One thing we can learn is that "core" seems to be a de facto standard=20
for the core clock-name. An alternative "gpu" is used by =
nvidia,gk20a.txt.

BR and thanks,
Nikolaus