linux-kernel - Re: [PATCH 2/3] dt-bindings: usb: atmel: Add Microchip LAN966x compatible string

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Message-ID: <20220520142109.57b84da2@bootlin.com>
Date:   Fri, 20 May 2022 14:21:09 +0200
From:   Herve Codina <herve.codina@...tlin.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 2/3] dt-bindings: usb: atmel: Add Microchip LAN966x
 compatible string

Hi Krzysztof,

On Fri, 20 May 2022 13:40:13 +0200
Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:

> On 20/05/2022 13:34, Herve Codina wrote:
> > On Fri, 13 May 2022 14:57:55 +0200
> > Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:
> >   
> >> On 13/05/2022 12:58, Herve Codina wrote:  
> >>> The USB device controller available in the Microchip LAN966x SOC
> >>> is the same IP as the one present in the SAMA5D3 SOC.
> >>>
> >>> Add the LAN966x compatible string and set the SAMA5D3 compatible
> >>> string as a fallback for the LAN966x.
> >>>
> >>> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> >>> ---
> >>>  Documentation/devicetree/bindings/usb/atmel-usb.txt | 3 +++
> >>>  1 file changed, 3 insertions(+)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/usb/atmel-usb.txt b/Documentation/devicetree/bindings/usb/atmel-usb.txt
> >>> index f512f0290728..a6fab7d63f37 100644
> >>> --- a/Documentation/devicetree/bindings/usb/atmel-usb.txt
> >>> +++ b/Documentation/devicetree/bindings/usb/atmel-usb.txt
> >>> @@ -87,6 +87,9 @@ Required properties:
> >>>  	       "atmel,at91sam9g45-udc"
> >>>  	       "atmel,sama5d3-udc"
> >>>  	       "microchip,sam9x60-udc"
> >>> +	       "microchip,lan996x-udc"    
> >>
> >> No wildcards please, especially that it closely fits previous wildcard
> >> (lan996x includes lan9960 which looks a lot like sam9x60...)
> >>  
> > 
> > Well, first, I made a mistake. It should be lan966x instead of lan996x.
> > 
> > This family is composed of the LAN9662 and the LAN9668 SOCs.
> > 
> > Related to the wilcard, lan966x is used in several bindings for common
> > parts used by both SOCs:
> > - microchip,lan966x-gck
> > - microchip,lan966x-cpu-syscon
> > - microchip,lan966x-switch
> > - microchip,lan966x-miim
> > - microchip,lan966x-serdes
> > - microchip,lan966x-pinctrl  
> 
> And for new bindings I pointed that it is not preferred, so already few
> other started using specific compatible.
> 
> > 
> > I think it makes sense to keep 'microchip,lan966x-udc' for the USB
> > device controller (same controller on LAN9662 and LAN9668) and so
> > keeping the same rules as for other common parts.  
> 
> Having wildcard was rather a mistake and we already started correcting
> it, so keeping the "mistake" neither gives you consistency, nor
> correctness...
> 

I think that the "family" compatible should be present.
This one allows to define the common parts in the common
.dtsi file (lan966x.dtsi in our case).

What do you think about:
- microchip,lan9662-udc
- microchip,lan9668-udc
- microchip,lan966-udc  <-- Family

lan966 is defined as the family compatible string since (1) in
bindings/arm/atmel-at91.yaml and in Documentation/arm/microchip.rst

(1) https://lore.kernel.org/all/20211004105926.5696-1-kavyasree.kotagiri@microchip.com/

Regards,
Herve

-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com