RE: [PATCH v7 1/6] dt-bindings: mailbox: allow mbox-cells to be equal to 0

[A.s. Dong]

> -----Original Message-----
> From: Jassi Brar [mailto:jassisinghbrar@xxxxxxxxx]
> Sent: Thursday, July 26, 2018 7:37 PM
> To: A.s. Dong <aisheng.dong@xxxxxxx>
> Cc: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>; Shawn Guo
> <shawnguo@xxxxxxxxxx>; Fabio Estevam <fabio.estevam@xxxxxxx>; Rob
> Herring <robh+dt@xxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>;
> Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>; Sudeep Holla
> <sudeep.holla@xxxxxxx>; Devicetree List <devicetree@xxxxxxxxxxxxxxx>;
> Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; , Sascha Hauer
> <kernel@xxxxxxxxxxxxxx>; , linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-
> mediatek@xxxxxxxxxxxxxxxxxxx, srv_heupstream <linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>
> Subject: Re: [PATCH v7 1/6] dt-bindings: mailbox: allow mbox-cells to be
> equal to 0
> 
> On Thu, Jul 26, 2018 at 4:30 PM, A.s. Dong <aisheng.dong@xxxxxxx> wrote:
> >> -----Original Message-----
> >> From: Jassi Brar [mailto:jassisinghbrar@xxxxxxxxx]
> >> Sent: Thursday, July 26, 2018 5:42 PM
> >> To: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
> >> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>; Fabio Estevam
> >> <fabio.estevam@xxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; Mark
> >> Rutland <mark.rutland@xxxxxxx>; A.s. Dong <aisheng.dong@xxxxxxx>;
> >> Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>; Sudeep Holla
> >> <sudeep.holla@xxxxxxx>; Devicetree List <devicetree@xxxxxxxxxxxxxxx>;
> >> Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; , Sascha
> >> Hauer <kernel@xxxxxxxxxxxxxx>; ,
> >> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-
> >> mediatek@xxxxxxxxxxxxxxxxxxx, srv_heupstream <linux-arm-
> >> kernel@xxxxxxxxxxxxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>
> >> Subject: Re: [PATCH v7 1/6] dt-bindings: mailbox: allow mbox-cells to
> >> be equal to 0
> >>
> >> On Thu, Jul 26, 2018 at 12:23 PM, Oleksij Rempel
> >> <o.rempel@xxxxxxxxxxxxxx>
> >> wrote:
> >> > From: Dong Aisheng <aisheng.dong@xxxxxxx>
> >> >
> >> > Mailbox devices may have only one channel which means the
> >> > mbox-cells at least 1 does not make sense for this type devices.
> >> > Let's remove that limitation to allow the mbox-cells to be equal to 0.
> >> >
> >> OK
> >>
> >> But please realise that you'll have to write more code -- implement
> >> your own
> >> of_xlate() callback.
> >> Most developers would prefer to call the only channel as channel
> >> number 0, and use the common of_xlate implementation.
> >>
> >
> > Yes, that's true because the common of_xlate assuming the mbox-cells is 1.
> > And there's already such users:
> > arch/arm/boot/dts/bcm283x.dtsi
> >
> You mean that is a good thing, right?

No, I mean there's similar HW in kernel already that only has one channel.
Are you suggesting even for one channel mailbox, we should still use
Mbox-cells 1 and use 'mboxes = <&mailbox 0>' in devicetree?

Regards
Dong Aisheng