[PATCH 3/3] ARM: dt: tegra: paz00: add regulators
thierry.reding at avionic-design.de
Mon Jun 25 07:07:45 EDT 2012
On Sun, Jun 24, 2012 at 03:27:42PM +0200, Marc Dietrich wrote:
> On Sunday 24 June 2012 13:31:51 Mark Brown wrote:
> > On Sun, Jun 24, 2012 at 02:01:58PM +0200, Marc Dietrich wrote:
> > > On Sunday 24 June 2012 12:03:06 Mark Brown wrote:
> > > > > > + regulator-name = "+3.3vs_ldo0";
> > > > > > + regulator-max-microvolt = <3300000>;
> > > >
> > > > This is one example, it looks like the rail needs to be fixed to 3.3V.
> > >
> > > I think nowhere in the code a regulator (beside sm*) is programmed to some
> > > different value that the maximum given here (this is not the maximum the
> > > regulator can provide). I never understood why the kernel code always sets
> > > the regulator to the maximum value if no other value was specified. IMHO,
> > > there should be some initial value, e.g. regulator-default-microvolt, as
> > > the original driver (from 2.6.32 ages) did. This way the maximum value
> > > can be set
> > That's *never* been in mainline, and nobody even bothered trying to
> > submit it.
> which was the best thing to do ;-)
> > > to the hw limits, but maybe this is a bit dangerous.
> > One of two things should be happening. Either a single voltage is
> > specified (in which case that voltage will be configured in the
> I'm not an expert on this, but it seems to me that only sm0 and sm1 should be
> changeable (and some rail called vdd_aon, which seems to be ldo2 in case of
> paz00 connected to the rtc). So, all others can be constant voltage. Maybe
> Stephen can comment on the actual requirements (also for the other boards
> which may have similar layout).
I can confirm that at least for ldo0 the value needs to be fixed. I did
in fact post a patch back in February that was needed to fix PCIe on
Harmony. I also sat down with one of our hardware engineers and worked
through the list and wrote down the requirements for Harmony. I need to
check where our notes have gone, though.
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