[U-Boot] [PATCH] mx23: Put back RAM voltage level to its original value

[Marek Vasut]

Dear Stefano Babic,

> On 27/04/2013 01:33, Marek Vasut wrote:
> > Dear Otavio Salvador,
> 
> Hi Fabio, Otavio, Marek,
> 
> >> On Fri, Apr 26, 2013 at 5:58 PM, Marek Vasut <marex at denx.de> wrote:
> >>> Dear Otavio Salvador,
> >>> 
> >>>> On Fri, Apr 26, 2013 at 5:08 PM, Fabio Estevam <festevam at gmail.com> 
wrote:
> >>>>> On Fri, Apr 26, 2013 at 3:16 PM, Marek Vasut <marex at denx.de> wrote:
> >>>>>> strange at best and I don't like it. I think that's also the source
> >>>>>> of our problems, the DRAM suffers undervolt and quickly afterwards
> >>>>>> is configured for regular operation ... I'd say check
> >>>>>> mx23_mem_setup_vddmem() and inspect the result with a scope. I think
> >>>>>> we need some slow ramping function like mxs_power_set_vddx().
> >>>>> 
> >>>>> Ok, but can we have this patch applied and do this investigation in
> >>>>> parallel?
> >>>>> 
> >>>>> At least we could have U-boot usable on mx23 again.
> >>>> 
> >>>> I also vote for it to be applied and then do this investigation in
> >>>> parallel. Even if there're still pending issues it does improve the
> >>>> current status.
> >>> 
> >>> But someone has to do this! And so far I see noone capable/willing to
> >>> do that :(
> >> 
> >> Oh really? Fabio, other people and me are doing it. We have some
> >> people helping to debug it and using their time to help testing it so
> >> it seems like a false accusation.
> > 
> > it == grabbing a scope and doing the real measurement :(
> > 
> >> So as I said, I see no reason to not get this patch in for now.
> > 
> > I am not against in per-se. I am worried noone will come up with real fix
> > when there is a "good enough plaster" put on to cover the real problem.
> 
> I agree that we have not yet found a clear cause of the behavior - but
> ler me say that is quite bound to the hardware and how voltage is
> applied to the DDR. As the patch reports to allow to boot kernel in most
> cases, I agree with Fabio to apply this - and IMHO most investigation
> should be done by the hardware developers.

Yes, I am already pestering Tsvetan to stop lazing around and do the measurement 
;-) Actually, CCed.

So far, we only have the VDDMEM graph which doesn't look nice :-(

Best regards,
Marek Vasut