Messages in this thread | | | 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 |
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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
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