Re: [PATCH 1/3] dt-bindings: usb: Add binding for TI USB8041 hub controller

Krzysztof Kozlowski
2022-07-12T21:32:18Z

On 12/07/2022 23:25, Matthias Kaehlcke wrote:
> On Tue, Jul 12, 2022 at 11:12:06PM +0200, Krzysztof Kozlowski wrote:
>> On 12/07/2022 19:25, Matthias Kaehlcke wrote:
>>> Hi Alexander,
>>>
>>> On Tue, Jul 12, 2022 at 05:06:25PM +0200, Alexander Stein wrote:
>>>> The TI USB8041 is a USB 3.0 hub controller with 4 ports.
>>>>
>>>> This initial version of the binding only describes USB related aspects
>>>> of the USB8041, it does not cover the option of connecting the controller
>>>> as an i2c slave.
>>>>
>>>> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
>>>> ---
>>>> Well, this is essentially a ripoff of
>>>> Documentation/devicetree/bindings/usb/realtek,rts5411.yaml with USB IDs
>>>> replaced, reset-gpio added and example adjusted.
>>>> IMHO this should be merged together with realtek,rts5411.yaml. Is it ok
>>>> to rename bindings files? I guess a common onboard-usb-hub.yaml matching
>>>> the driver seens reasonable. Any recommendations how to proceed?
>>>
>>> It's a tradeoff between keeping the individual bindings simple and avoid
>>> unnecessary duplication. The current RTS5411 and TI USB8041 bindings are
>>> very similar, which suggests combining them. However over time hubs with
>>> diverging features could be added (e.g. with multiple regulators, a link
>>> to an I2C/SPI bus, a clock, ...). With that a common binding might become
>>> too messy.
>>>
>>> From a quick look through Documentation/devicetree/bindings it doesn't
>>> seem common to have generic bindings that cover components from multiple
>>> vendors. In that sense I'm leaning towards separate bindings.
>>>
>>> Rob, do you have any particular preference or suggestion?
>>
>> Not Rob, but my suggestion is not to merge bindings of unrelated
>> devices, even if they are the same class. By unrelated I mean, made by
>> different companies, designed differently and having nothing in common
>> by design. Bindings can be still similar, but should not be merged just
>> because they are similar.
>
> Thanks for your advice, let's keep separate bindings then.

Although for the record let me add that we did merge some trivial hwmon
devices like LM75 or LM90 but their bindings are trivial and programming
model is also similar between each other (handled by same device
driver). I guess we can be here flexible, so the question would be how
similar these USB hubs are.

If in doubt, just keep it separate.

Best regards,
Krzysztof