[U-Boot] i.MX6 DRAM_RESET documentation

Troy Kisky troy.kisky at boundarydevices.com
Tue Jul 16 23:59:29 CEST 2013


Hi All

I have a strange issue that maybe you can help explain. Under u-boot 
during a tftp transfer,
we have some boards that show timeouts on our latest build, and 1 board
where ethernet doesn't work at all on the latest build. These boards 
work with
an older rev of software. I was able to compare the two versions until I 
found the
relevant change that caused the problem. It was the setting for
IOMUXC_SW_PAD_CTL_PAD_DRAM_RESET.

The working code uses a value of 00b for this field. When I changed it 
to 11b,
things broke. In the documentation, this register is defined differently for
mx6q vs mv6solo/duallite. The duallite way works for the quad, and either
way works for the duallite.

board/boundary/nitrogen6x/ddr-setup.cfg:DATA 4, MX6_IOM_DRAM_RESET, 
0x000e0030

board/freescale/imx/ddr/mx6q_4x_mt41j128.cfg:DATA 4 0x020e057c 0x00020030


Who's right? And should it depend on quad vs duallite ?
Currently, I believe that the duallite documentation is correct for all.


Thanks
Troy


IMX6DQRM-04-2013.pdf has the field defined
as below
IOMUXC_SW_PAD_CTL_PAD_DRAM_RESET field descriptions
31–20 : This read-only field is reserved and always has the value 0.
19–18 : DDR Select Field
Select one of next values for pad: DRAM_RESET.
00 RESERVED0 — Reserved
01 RESERVED1 — Reserved
10 LPDDR2 — LPDDR2 mode (240 Ohm driver unit calibration, 240, 120, 80, 
60, 48, 40, 32 Ohm drive
strengths at 1.2V)
11 DDR3 — DDR3 mode (240 Ohm driver unit calibration, 240, 120, 80, 60, 
48, 40, 32 Ohm drive
strengths at 1.5V)
___________________________________
mx6solo-Reference Manual Addendum Rev A.2.pdf has
the field defined as below

IOMUXC_IOMUXC_SW_PAD_CTL_PAD_DRAM_RESET field descriptions
Field Description
31–22 : This field is reserved.
21–20 : DO_TRIM Read Only Field 0 0
19–18 : DDR Select Field
Select one out of next values for pad: DRAM_RESET.
00 LPDDR1 / DDR3 / (DDR2 ODT) modes
01 DDR2 driver mode
10 LPDDR2 mode
11 Reserved



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