Re: [PATCH v2 1/4] dt: bindings: mmc: Document the practice of using subnodes for slots

On Sun, Jun 01, 2014 at 11:23:48AM +0200, Hans de Goede wrote:

Hi,

quoted

Neither seems to actually ever have been used with
more than one slot. I doubt anyone building an exynos-based system
will ever do a multi-slot solution, and it seems that the at91 driver
doesn't actually handle more than one slot.

I'm personally not that excited about complicating the bindings by
opening up for this -- I would rather work towards removing the
concept of slots if it's one of those things that are going to remain
unused. We have actually been talking about reworking the dw_mmc
binding to remove the slot concept (and simplify the driver by doing
so).

I'm fine with removing the slot subnode, I added it because of it being
brought up in the powerup sequence discussion. I explicitly asked there
if adding such a subnode level was seen as desirable but nobody
answered :|

MMC bus support was removed back in 2007:

| commit b855885e3b60cf6f9452848712a62517b94583eb
| Author: Pierre Ossman [off-list ref]
| Date:   Wed Jan 3 19:47:29 2007 +0100
| 
|     mmc: deprecate mmc bus topology
|     
|     The classic MMC bus was defined as multi card bus
|     system, which is reflected in the design in the MMC
|     layer.
|     
|     When SD showed up, the bus topology was abandoned
|     and a star topology (one card per host) was mandated.
|     MMC version 4 has followed this, officially deprecating
|     the bus topology.
|     
|     As we do not have any known users of the bus
|     topology we can remove support for it. This will
|     simplify the code and rectify some incorrect
|     assumptions in the newer additions.
|     
|     Signed-off-by: Pierre Ossman [off-list ref]

I doubt we will ever need support for it.

Sascha

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