Re: [patch 2.6.29-rc5-omap-git] mach-omap2/mmc-twl4030: fix for vmmc = 0

[David Brownell <david-b@pacbell.net>]

On Tuesday 24 February 2009, Adrian Hunter wrote:
> David Brownell wrote:
> > From: David Brownell <dbrownell@users.sourceforge.net>
> > 
> > Resolve longstanding issue noted by Adrian Hunter:  confusion
> > between settting VSEL=0 (which is 1.8V on MMC1) and poweroff.
> > 
> > Also, leave VSEL alone if we're just powering the regulator off.
> > 
> > Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
> > ---
> 
> Looks fine to me, but I wonder if you know why the regulator is
> turned on (DEV_GRP) and then the voltage is selected (DEDICATED).

History, I'd guess.  I seem to remember some sequencing
constraint, but couldn't find it when last I sought it
out in the reference manual.


> Wouldn't it make more sense the other way around?

I had the same thought.  Eventually I'd like this code
to mostly wither away ... using the regulator framework
for the hsmmc driver will eliminate most of the remaining
bits of twl4030-specific code.  So I'd just leave it be
for the moment.


> Doesn't the new regulator framework do it that way?

No; setting voltage and enabling are distinct operations.