How to Create i.MX6 32bit DDR3 Script Based on 64bit DDR3 Script

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Overview

i.MX6Dual/Quad and i.MX6DualLite supports 32-bit and 64-bit DDR3. Freescale i.MX6 SabreSD board deploys 64bit DDR3 and 64bit DDR3 script is delivered into Linux/Android Software release. This document introduces how to create i.MX6 32bit DDR script based on 64bit DDR script when deploying 32bit DDR on customized board.

Changes

• Set the DSE field in the following iomux registers to 0 - disable unused IO pad to save power:

IOMUXC_SW_PAD_CTL_PAD_DRAM_SDQS4

IOMUXC_SW_PAD_CTL_PAD_DRAM_SDQS5

IOMUXC_SW_PAD_CTL_PAD_DRAM_SDQS6

IOMUXC_SW_PAD_CTL_PAD_DRAM_SDQS7

IOMUXC_SW_PAD_CTL_GRP_B4DS

IOMUXC_SW_PAD_CTL_GRP_B5DS

IOMUXC_SW_PAD_CTL_GRP_B6DS

IOMUXC_SW_PAD_CTL_GRP_B7DS

IOMUXC_SW_PAD_CTL_PAD_DRAM_DQM4

IOMUXC_SW_PAD_CTL_PAD_DRAM_DQM5

IOMUXC_SW_PAD_CTL_PAD_DRAM_DQM6

IOMUXC_SW_PAD_CTL_PAD_DRAM_DQM7

• Update MMDC registers to reflect 32bit DDR changes:

MMDC0_MDASP: Update CS0_END if CS size is changed.

MMDC0_MDCTL: set DSIZ to 32 bit

MMDC1_MPODTCTRL: Set it as 0 and disable the odt of higher byte

• Follow "i.MX 6 Series DDR Calibration" Application note to calibrate DDR parameters.

Reference

One example about 32bit DDR script is located under uboot-imx git ( File: board/freescale/mx6q_sabresd/flash_header.S). Open it and you can see the following script:

#if defined CONFIG_MX6DL_DDR3

#if defined CONFIG_DDR_32BIT

...

#endif

You can refer to it and create your 32bit DDR script.