From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 5/10] dt: bindings: Add bindings for Marvell Xenon SD Host Controller Date: Thu, 24 Nov 2016 10:11:19 +0100 Message-ID: <4031579.CBE32NHUoW@wuerfel> References: <87d1hno2d7.fsf@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ulf Hansson Cc: Gregory CLEMENT , Rob Herring , Ziji Hu , Adrian Hunter , "linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Jason Cooper , Andrew Lunn , Sebastian Hesselbarth , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Thomas Petazzoni , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "Jack(SH) Zhu" , Jimmy Xu , Jisheng Zhang , Nadav Haklai , Ryan Gao , Doug Jones , Shiwu Zhang , Vi List-Id: devicetree@vger.kernel.org On Thursday, November 24, 2016 10:05:45 AM CET Ulf Hansson wrote: > > You also mentioned other bindings using child nodes, but for this one > > we have one controller with only one set of register with multiple slots > > (Atmel is an example). Here each slot have it own set of register. > > > > Actually giving the fact that each slot is controlled by a different set > > of register I wonder why the hardware can't also deduce the slot number > > from the address register. For me it looks like an hardware bug but we > > have to deal with it. > > > > Do you still think we needchild node here? > > Using child-nodes for slots like what's done in the atmel case, is > currently broken. I would recommend to avoid using child-nodes for > slots, if possible. > > To give you some more background, currently the mmc core treats child > nodes as embedded non-removable cards or SDIO funcs. However, we can > change to make child-nodes also allowed to describe slots, but it > requires a specific compatible for "slots" and of course then we also > need to update the DT parsing of the child-nodes in the mmc core. > > Documentation/devicetree/bindings/mmc/mmc.txt > Documentation/devicetree/bindings/mmc/mmc-card.txt I don't see anything wrong with having child nodes for the slots even with the current binding, under one condition: The mmc.txt binding above must refer only to the child node, while the parent node conceptually becomes a plain bus or MFD that happens to encapsulate multiple MMC host controllers, and possibly provides some shared registers to them. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html