topic Re: SabreSD: Adding DCD item to u-boot in i.MX Processors

SabreSD: Adding DCD item to u-boot

ts — Wed, 27 Feb 2013 00:52:09 GMT

Hi,

For testing adding a DCD Item, i modified flash_header.S to add one more DCD item to modify ENET_PALR, after the 83rd item (SabreSD, i.mx6Q):

MXC_DCD_ITEM(84, 0x021880E4, 0xFFFFFFFF)

I updated dcd_hdr and write_dcd_cmd as:

dcd_hdr:	.word 0x40a802D2
write_dcd_cmd:	.word 0x04A402CC

The u-boot now fails to boot up. If i modify the 84th DCD Item to be the same as the 83rd DCD item (i.e. configuring DDR) it works.

Are there limitations to what registers can be updated by the ROM from the DCD list, or am i missing something?

thanks

Re: SabreSD: Adding DCD item to u-boot

Yuri — Wed, 27 Feb 2013 06:00:24 GMT

Please look at Table 8-35 (Valid DCD Address Ranges) in i.MX6Q Reference Manual.

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf?fpsp=1

Re: SabreSD: Adding DCD item to u-boot

RodBorras — Wed, 27 Feb 2013 15:41:59 GMT

Tarak,

You are only using 680 of the 1768 DCD bytes, so you should be fine.

But modifying the MAC address might have boot repercussions, especially if you are trying an NFS mount.

If your goal is to just modify some generic registers in the DCD, try something more benign. I do not see why you cannot change just about anything you want, in there.

Regards,

Rod.

Re: SabreSD: Adding DCD item to u-boot

fabio_estevam — Wed, 27 Feb 2013 18:17:21 GMT

Why exactly do you need to touch ENET_PALR from the DCD? What is the issue you are trying to solve?

Re: SabreSD: Adding DCD item to u-boot

ts — Wed, 27 Feb 2013 18:48:19 GMT

Rod, apparently not all addresses can be accessed as indicated by Yuri's link to table 8-35.

Re: SabreSD: Adding DCD item to u-boot

RodBorras — Wed, 27 Feb 2013 19:19:51 GMT

Tarak: thank you for pointing this out to me, I was unaware of it.

Yuri: my apologies, I misunderstood your post, and did not realize it contained the answer.