On Thu, Jul 26, 2018 at 5:25 PM, A.s. Dong <aisheng.d...@nxp.com> wrote: >> -----Original Message----- >> From: Jassi Brar [mailto:jassisinghb...@gmail.com] >> Sent: Thursday, July 26, 2018 7:37 PM >> To: A.s. Dong <aisheng.d...@nxp.com> >> Cc: Oleksij Rempel <o.rem...@pengutronix.de>; Shawn Guo >> <shawn...@kernel.org>; Fabio Estevam <fabio.este...@nxp.com>; Rob >> Herring <robh...@kernel.org>; Mark Rutland <mark.rutl...@arm.com>; >> Vladimir Zapolskiy <vladimir_zapols...@mentor.com>; Sudeep Holla >> <sudeep.ho...@arm.com>; Devicetree List <devicet...@vger.kernel.org>; >> Linux Kernel Mailing List <linux-kernel@vger.kernel.org>; , Sascha Hauer >> <ker...@pengutronix.de>; , linux-arm-ker...@lists.infradead.org, linux- >> media...@lists.infradead.org, srv_heupstream <linux-arm- >> ker...@lists.infradead.org>; dl-linux-imx <linux-...@nxp.com> >> 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.d...@nxp.com> wrote: >> >> -----Original Message----- >> >> From: Jassi Brar [mailto:jassisinghb...@gmail.com] >> >> Sent: Thursday, July 26, 2018 5:42 PM >> >> To: Oleksij Rempel <o.rem...@pengutronix.de> >> >> Cc: Shawn Guo <shawn...@kernel.org>; Fabio Estevam >> >> <fabio.este...@nxp.com>; Rob Herring <robh...@kernel.org>; Mark >> >> Rutland <mark.rutl...@arm.com>; A.s. Dong <aisheng.d...@nxp.com>; >> >> Vladimir Zapolskiy <vladimir_zapols...@mentor.com>; Sudeep Holla >> >> <sudeep.ho...@arm.com>; Devicetree List <devicet...@vger.kernel.org>; >> >> Linux Kernel Mailing List <linux-kernel@vger.kernel.org>; , Sascha >> >> Hauer <ker...@pengutronix.de>; , >> >> linux-arm-ker...@lists.infradead.org, linux- >> >> media...@lists.infradead.org, srv_heupstream <linux-arm- >> >> ker...@lists.infradead.org>; dl-linux-imx <linux-...@nxp.com> >> >> 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.rem...@pengutronix.de> >> >> wrote: >> >> > From: Dong Aisheng <aisheng.d...@nxp.com> >> >> > >> >> > 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? > As i said, I am ok with the mbox-cells to be 0.
But if you have two instances of the controller, one with 4 channels and the other with 1 channel. Then you can/should not have different bindings. And, if the controller can have only 1 channel, then please feel free to have mbox-cells=0 and implement your own of_xlate().
