linux-kernel - Re: [PATCH 2/2] dt-bindings: clock: intel,cgu-lgm: add mxl,control-gate option

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Date:   Sat, 5 Aug 2023 21:09:54 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Florian Eckert <fe@....tdt.de>
Cc:     mturquette@...libre.com, sboyd@...nel.org, yzhu@...linear.com,
        rtanwar@...linear.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Eckert.Florian@...glemail.com
Subject: Re: [PATCH 2/2] dt-bindings: clock: intel,cgu-lgm: add
 mxl,control-gate option

On 01/08/2023 10:09, Florian Eckert wrote:
> Hello Krzysztof,
> 
>>>> You described the desired Linux feature or behavior, not the actual
>>>> hardware. The bindings are about the latter, so instead you need to
>>>> rephrase the property and its description to match actual hardware
>>>> capabilities/features/configuration etc.
>>>
>>> You have correctly identified that this is not a hardware 
>>> configuration,
>>> but a driver configuration. Currently, the driver is configured so 
>>> that
>>> the gates cannot be switched via the clk subsystem callbacks. When
>>> registering the data structures from the driver, I have to pass a flag
>>> GATE_CLK_HW so that the gate is managed by the driver.
>>>
>>> I didn't want to always change the source of the driver when it has to
>>> take
>>> care of the GATE, so I wanted to map this via the dts.
>>>
>>> I have a board support package from Maxlinear for the Lightning 
>>> Mountain
>>> Soc
>>> with other drivers that are not upstream now. Some of them use the
>>> clock framework some of them does not.
>>>
>>> Due to missing documents it is not possible to send these drivers
>>> upstream.
>>
>> So when you upstream them, the binding becomes wrong or not needed?
>> Sorry, bindings are entirely independent of OS, so using this as an
>> argument is clear no-go.
> 
> Yes, that would probably be the case, as the maxlinear drivers are at
> an early stage and are not yet upstreamable in my opinion. If I had the
> documents, I would take a closer look. But they are developing behind
> closed doors. Nothing can be contributed. Not until the drivers are
> hopefully upstream at some point as the cgu-lgm.
> 
>>> Strictly speaking, this is about the gptc and the watchdog.
>>>
>>> Since it is a buildin_platform driver, it can also not work via
>>> module parameters.
>>
>> None of this explains any hardware related part of this binding. You
>> created now policy for one specific OS. Devicetree, which is OS
>> independent, is not for such purposes.
> 
> Yes this would be the case. Maybe I need to patch the cgu-lgm.c [1]
> and send it upstream to restore the old behavior.
> Because the following commit has changed the behaviour [2].
> Unfortunately, it is also included in 5.15 stable branch.
> Which in my opinion should not have happened!

Then unfortunately this is not a correct change.

Best regards,
Krzysztof