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

[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.

Best regards,
Stefano

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