[PATCH/RFC] mmc: add DT bindings for more MMC capability flags

[Guennadi Liakhovetski]

On Thu, 7 Feb 2013, Arnd Bergmann wrote:

> On Wednesday 06 February 2013 17:25:42 Guennadi Liakhovetski wrote:
> > 
> > Thank for pointing me out at that thread. However, I don't think 
> > MMC_CAP_POWER_OFF_CARD has anything to do with compatibility or hardware 
> > revisions. At least I haven't yet come across any sd/mmc hosts, that also 
> > supply card power. You could "derive" this flag from the presence of a 
> > regulator, capable of changing its status (switching on / off), but even 
> > then you're not guaranteed, that you actually can (and want to) power the 
> > card off at run-time - the regulator can be shared etc. So, an explicit 
> > flag is needed.
> 
> It sounds like something that should be handled in a controller specific
> way I think. E.g. on SDHCI, there seems to always be a method to power
> down the card using the SDHCI_POWER_CONTROL register, even without
> any external regulators.

If I understand correctly, that register only controls card bus power. 
Further sdhci.c uses regulators (host->vmmc) to power up and down the 
card.

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/