[PATCH RFC 1/3] DT: bindings: mmc: Add property for 3.3V only support

[Stefan Wahren]

Hi,

> Rob Herring <robh at kernel.org> hat am 10. August 2016 um 20:44 geschrieben:
> 
> 
> On Sat, Aug 06, 2016 at 12:55:38PM +0000, Stefan Wahren wrote:
> > Currently there is no proper way to define that a MMC host supports
> > only 3.3V. The property no-1-8-v is broken and has different meanings
> > for different sdhci variants. So add a new property for 3.3V only
> > support and mark no-1-8-v as deprecated.
> 
> Why is it broken? 

i want to quote Ulf Hansson here [1]:

  The problem with the "no-1-8-v" binding is that it's describing what
  the hardware *can't* do. It thus becomes easy to abuse it.

  I suggest we stop using it, we should mark it deprecated.

[1] - http://www.spinics.net/lists/linux-mmc/msg34604.html

> How would I override a controller saying 1.8V is 
> supported and it is not?

Sorry, i'm not sure that i understand your question. In case a board or a MMC
controller doesn't support 1.8V, it usually supports only 3.3V which is the
intension of this patch.

> 
> Rob
> 
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