[U-Boot] [PATCH v2] mxs: fixed battery boot on imx233-olinuxino-micro

[Stefano Babic]

Hi Peter, hi Marek,

On 19/06/2014 09:12, Marek Vasut wrote:
> On Wednesday, June 18, 2014 at 08:17:05 PM, Peter Schumann wrote:
>> Am 17.06.2014 18:00, schrieb Stefano Babic:
>>> Hi peter,
>>> ...
>>> On 17/06/2014 00:19, Marek Vasut wrote:
>>> Agree. Reason is that this change is for all boards, and without a
>>> proper testing I will avoid to merge it in the release.
>>>
>>> Best regards,
>>> Stefano Babic
>>
>> Hi Stefano,
>>
>> I've only the imx233 olimex board for testing. The DOUBLE_FETS switch in
>> HW_POWER_MINPWR is some thing were maybe problems emerge.
>>
>> I have very little load on the powerrails (imx233 + DRAM), so maybe with
>> more current demand DOUBLE_FETS is working OK and even more may require
>> it to be set.
> 
> If that was the case, the problem would manifest even when _not_ booting from 
> battery-only supply, correct?
> 
>> The DOUBLE_FETS and HALF_FETS switches control the switching MOSFET size
>> in the DCDC Converter. My assumption is that if we have a to big FET
>> setting and to low current demand we trigger some failsafe mechanism.
>> Because the required "on time" of the FET is smaller than the minimum
>> possible "on time" of then DCDC FET control logic.
>>
>> I don't have an easy way to test this assumption without an adjustable
>> load.
>>
>> The other change regarding mxs_power_enable_4p2() should be relatively
>> safe to apply.
> 
> This breaks booting from battery on MX28 for some reason. The DC converter is 
> not enabled at that point.

As I have not (yet) forgotten this patch: current status is that mx28 is
broken after applying this patch. I set the status as "Changes
requested" and it will be not applied.

Best regards,
Stefano Babic




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