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Message-ID: <8c4a488e-8990-8ad2-e82b-8759c9b85447@linaro.org>
Date: Tue, 18 Jul 2023 15:06:03 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Frank Binns <Frank.Binns@...tec.com>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
Sarah Walker <Sarah.Walker@...tec.com>
Cc: "luben.tuikov@....com" <luben.tuikov@....com>,
"christian.koenig@....com" <christian.koenig@....com>,
"krzysztof.kozlowski+dt@...aro.org"
<krzysztof.kozlowski+dt@...aro.org>,
"tzimmermann@...e.de" <tzimmermann@...e.de>,
"mripard@...nel.org" <mripard@...nel.org>,
"matthew.brost@...el.com" <matthew.brost@...el.com>,
"daniel@...ll.ch" <daniel@...ll.ch>,
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<maarten.lankhorst@...ux.intel.com>, "afd@...com" <afd@...com>,
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Donald Robson <Donald.Robson@...tec.com>,
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Subject: Re: [PATCH v4 02/17] dt-bindings: gpu: Add Imagination Technologies
PowerVR GPU
On 18/07/2023 13:32, Frank Binns wrote:
> Hi Krzysztof,
>
> On Mon, 2023-07-17 at 09:29 +0200, Krzysztof Kozlowski wrote:
>> On 14/07/2023 16:25, Sarah Walker wrote:
>>> Add the device tree binding documentation for the Series AXE GPU used in
>>> TI AM62 SoCs.
>>>
>>
>> ...
>>
>>> +
>>> + clocks:
>>> + minItems: 1
>>> + maxItems: 3
>>> +
>>> + clock-names:
>>> + items:
>>> + - const: core
>>> + - const: mem
>>> + - const: sys
>>> + minItems: 1
>>
>> Why clocks for this device vary? That's really unusual to have a SoC IP
>> block which can have a clock physically disconnected, depending on the
>> board (not SoC!).
>
> By default, this GPU IP (Series AXE) operates on a single clock (the core
> clock), but the SoC vendor can choose at IP integration time to run the memory
> and SoC interfaces on separate clocks (mem and sys clocks respectively). We also
> have IP, such as the Series 6XT, that requires all 3 clocks.
Currently you have only one SoC vendor with only one SoC, so the clocks
do not vary. Describing the clocks for all possible variants is a good
idea, but then this should be clear that this implementation uses subset.
>
> So the situation here is that Series AXE may have 1 or 3 clocks, but the TI
> implementation being added only has 1.
>
> I guess we need to add something like:
>
> allOf:
> - if:
> properties:
> compatible:
> contains:
> const: ti,am62-gpu
> then:
> properties:
> clocks:
> maxItems: 1
>
> Or should we be doing something else?
Yes. clock-names as well..
Best regards,
Krzysztof
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