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Subject: Re: [PATCH v7 01/12] dt-bindings: add img,pvrsgx.yaml for Imagination GPUs
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From:   "H. Nikolaus Schaller" <hns@goldelico.com>
In-Reply-To: <20200503150143.GG37466@atomide.com>
Date:   Fri, 15 May 2020 09:58:31 +0200
Cc:     Paul Cercueil <paul@crapouillou.net>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
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        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paulburton@kernel.org>,
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        Krzysztof Kozlowski <krzk@kernel.org>,
        Maxime Ripard <mripard@kernel.org>,
        Chen-Yu Tsai <wens@csie.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Jonathan Bakker <xc-racer2@live.ca>,
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To:     Tony Lindgren <tony@atomide.com>
Sender: linux-kernel-owner@vger.kernel.org
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Hi Tony,

> Am 03.05.2020 um 17:01 schrieb Tony Lindgren <tony@atomide.com>:
>=20
> * Paul Cercueil <paul@crapouillou.net> [200503 14:19]:
>> You have a new SoC with a SGX, and you only need to enable one clock =
to get
>> it to work. So you create a devicetree node which receives only one =
clock.
>>=20
>> Turns out, that the bootloader was enabling the other 3 clocks, and =
since
>> the last release, it doesn't anymore. You're left with having to =
support a
>> broken devicetree.
>>=20
>> That's the kind of problem that can be easily avoided by enforcing =
the
>> number of clocks that have to be provided.
>=20
> The number of clocks depends on how it's wired for the SoC.
>=20
> On omaps, there's are no controls for additinoal SGX clocks. Sure some
> of the clocks may be routed to multple places internally by the =
wrapper
> module. But we have no control over that.
>=20
> If we wanted to specify just the "fck" clock on omaps, then we can
> do it with something like this:
>=20
> allOf:
>  - if:
>    properites:
>      compatible:
>        enum:
> 	  - "ti,omap4-sgx544-112"
> 	  - "ti,omap5-sgx544-116"
> 	  - "ti,dra7-sgx544-116"
>    then:
>      properties:
>        clocks:
> 	  minItems: 1
> 	  maxItems: 1
>=20
>        clock-names:
> 	  const: fck
>=20
>    required:
>      - clocks
>      - clock-names

will add to v8 of this series as a separate patch on top of the
general one. This should make it easier to have a focussed discussion
and revert/bisect if something goes wrong.

BR and thanks,
Nikolaus