[U-Boot] [PATCH RFC] arm: mx6: Add CCGR0 configuration to default DCD (spl_sd.cfg)

[Stefan Roese]

Hi Fabio,

On 08.12.2014 15:15, Fabio Estevam wrote:
> On Mon, Dec 8, 2014 at 11:31 AM, Stefan Roese <sr at denx.de> wrote:
>> While switching a custom i.MX6DL board port to the common mx6
>> infrastructure without any board specific DCD file (*.cfg), booting
>> from SD-card (mmc0) via the bmode command (bmode mmc0) did not work
>> any more. Adding this one line for the CCGR0 solves this issue.
>>
>> I have to admit that I'm not really sure why this is needed in
>> this case. So if somebody has an explanation for the need for
>> this CCGR0 register setup in the DCD, then please let me know.
>
> Could you please try to narrow down what exact field of the CGR0
> register makes your board boot?
>
> I suspect it could be the AIPS related clocks (CG0 / CG1).

I tested with these values:

0x00C03F30
0x00C03F33
0x00C03F3C

All do not boot. Only the original one does:

0x00C03F3F

So yes, AIPS related clocks are definitely needed!

I'm wondering about this, since the default value after reset should be 
0xffffffff for this register, right? All clocks enabled. But this does 
not seem to be the case. As SPL is not started correctly (no output at 
all on the console) when I don't add this line to spl_sd.cfg.

Its not easy for me to debug this issue since the board usually boots 
from NAND. I can't strap this board to boot via MMC0 right now. So I 
have to use the "bmode mmc0" command. And JTAG debugging via BDI3000 
doesn't seem to "survive" the bmode command.

> Please confirm. If this is the case, then we should turn on the AIPS
> clocks inside init_aips().

See above.

Could you test this on one of your board? If your board also fails to 
boot via the "bmode mmc0" command if the CCGR0 register value is missing?

Thanks,
Stefan