Re: Any news on Runtime Interpreted Power Sequences

From: Mark Brown
Date: Mon Oct 28 2013 - 19:54:25 EST

On Mon, Oct 28, 2013 at 10:10:04PM +1100, NeilBrown wrote:

> I agree that this power-up sequence should be a property of the device.
> However until the device has been powered up, Linux doesn't know about it.
> Neither a board file or a devicetree can (as far as I can tell), tell the
> MMC port that a particular card is attached. Rather the host probes the card
> to see what it is.
> So there isn't any way for the device driver to get control at the
> appropriate time to effect the proper sequencing.

If it is a genuinely pluggable MMC slot then I'd expect the sequence to
be implementing whatever is required for standard MMC enumeration to
work. If the device is a soldered down one with extra control (as is
quite common) then there shouldn't be a problem describing it?

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