[U-Boot] i.MX6 DRAM_RESET documentation

[Liu Hui-R64343]

>-----Original Message-----
>From: Troy Kisky [mailto:troy.kisky at boundarydevices.com]
>Sent: Wednesday, July 17, 2013 5:59 AM
>To: Fabio Estevam
>Cc: Liu Hui-R64343; Benoît Thébaudeau; u-boot at lists.denx.de
>Subject: i.MX6 DRAM_RESET documentation
>
>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.
>

Both are not correct. The MMDC owner has known about this doc issue and will
Update them later. The correct is: 00 is the only valid data, others will be 
Reserved.


>
>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
>