[U-Boot] [PATCH 1/2] ARM: mxs: Enable DCDC converter for battery boot

[Marek Vasut <marex@denx.de>]

On Saturday, October 25, 2014 at 11:43:05 PM, Fabio Estevam wrote:
> Hi Michael,
> 
> On Thu, Oct 23, 2014 at 5:07 AM, Michael Thalmeier
> 
> <michael.thalmeier@hale.at> wrote:
> > Hi Marek, and Fabio
> > 
> >> > Shouldn't this be conditional?
> >> > 
> >> > #if defined CONFIG_MXS_ENABLE_4P2
> >> > mxs_power_enable_4p2();
> >> > #endif
> >> > 
> >> > Then the boards that need this power supply enable
> >> > CONFIG_MXS_ENABLE_4P2 in its config file.
> >> 
> >> No, we want to start the DCDC converter unconditionally when running on
> > 
> > battery
> > 
> >> power to increase efficiency.
> > 
> > I just stumbled upon this, because our board does not boot reliably any
> > more with this change.
> > Perhaps we have a special situation in that our board is powered via
> > DCDC_BATT only by an external power source (no battery).
> > 
> > I am currently working on creating a patch to only conditionally enabling
> > this feature, or to enable it by default and have it conditionally be
> > disabled for boards that are known to have problems with this.
> > 
> > Which approach seems to be more feasible to you?
> 
> Initially I proposed something like:
> 
> #if defined CONFIG_MXS_ENABLE_4P2
> mxs_power_enable_4p2();
> #endif
> 
> ,but Marek was not happy about it, so let's wait for his thoughts. Marek?

Can you share the schematic of your power distribution network ? I would like
to check a couple of things in there. I suspect there is a common problem with
MX23 and MX28 based designs discovered by Juha and I'd like to make sure you
don't suffer from it.

It's OK to send the schematic off-list.

Thanks!

Best regards,
Marek Vasut