[U-Boot] mx6ul_14x14_evk

[Eric Nelson]

Hi Fabio,

On 08/28/2016 07:47 PM, Fabio Estevam wrote:
> On Sun, Aug 28, 2016 at 6:04 PM, Eric Nelson <eric at nelint.com> wrote:
>> On 08/28/2016 01:59 PM, Eric Nelson wrote:
>>> Hi Fabio, Peng, and all.
>>>
>>> I just ran into a problem with bus frequency switching
>>> on the EVK and there appears to be a U-Boot component.
>>>
>>> Using the 4.1.15 kernel from git.freescale.com (commit a4d2a08)
>>> and the latest U-Boot from Stefano's imx tree (commit a3e5519)
>>> causes the EVK to hang during a bus frequency switch to LOW_POWER
>>> mode.
>>>
>>> The last gasp is this:
>>>       Bus freq set to 24000000 start...
>>>
>>> <snip>
>>>
>>> Has anybody else experienced this?
>>>
>> <snip>
> 
> I was able to reproduce this problem here.
> 
> The major difference between mainline U-Boot and NXP U-Boot is that
> mainline U-Boot uses SPL and NXP U-Boot uses imximage.cfg to configure
> the DDR.
> 

Right, and unfortunately, walking the differences can be time consuming.

> I have just created and tested the patch below against Stefano's tree:
> http://pastebin.com/crAe1Yr1
> 
> , which basically uses imximage.cfg from NXP U-Boot instead of SPL and
> the hang does not occur.
> 

Cool. That narrows things down a lot.

> It seems to me that we need to carefully review the SPL DDR init code
> in mainline in order to fix this problem.
> 

Or clock tree.

> I will try to take a look at it tomorrow, but if anyone spots the DDR
> problem in the SPL code, then feel free to submit the patch :-)
> 
Will do.

Regards,


Eric