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

[Fabio Estevam]

On Fri, Apr 26, 2013 at 3:16 PM, Marek Vasut <marex at denx.de> wrote:
> Dear Fabio Estevam,
>
>> On Fri, Apr 26, 2013 at 1:24 PM, Eric Bénard <eric at eukrea.com> wrote:
>> > what are the values of these levels (previous one and new one) in mV ?
>>
>> 0x10 ==> 2.5V
>> 0x12 ==> 2.6V
>>
>> 46v32m16
>
> Eh? What's this code above?

It is the DDR part number on mx23evk.

>
>> says that VDD is : 2.5V +/- 0.2V, so 2.6V is a valid supply
>> voltage.
>>
>> Not sure why 2.5V fails though.
>
> http://s8.postimg.org/dn7jhntut/imx233_olinuxino_maxi_2_5_V_rising.jpg check
> this, this is as much as I got from tsvetan so far, it's the VDDMEM ramping. I
> dunno what's that weird drop before it starts going from 1V5 to 2V5, but it's

Why 1.5V? The VDDMEM reset value is 1.7V.

> 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.