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

[Adrian Hunter <ext-adrian.hunter@nokia.com>]

David Brownell wrote:
> 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.

What about section 5.5.1 item 6?

>> 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.

Perhaps, but there are features like regulator constraints,
or the Virtual regulator that do set the voltage and then
enable.