AnsweredAssumed Answered

eMMC Normal boot not work with x4,x8 DDR setting.

Question asked by Takayuki Ishii on Dec 4, 2018
Latest reply on Dec 13, 2018 by Takayuki Ishii

Hello community,


I tested eMMC(rev 5.01) boot with i.mx6q sabre-sd USDHC2 I/F.

In fast boot mode (BOOT_CFG1[4] = 1), it can boot from boot partition both x8 and x4 DDR mode.

In normal boot mode (BOOT_CFG1[4] = 0) with x1,x4,x8 SDR mode, it can boot correctly.


But normal boot mode (BOOT_CFG1[4] = 0) with x4,x8 SDR mode, it can not boot both user partition and

boot partition of eMMC.

Base setting of USDHC boot eFUSE descriptions as following.

BOOT_CFG1[7:6] : 01 - boot from USDHC
BOOT_CFG1[5] : 1 - eMMC
BOOT_CFG1[4] : 0 - Normal boot
BOOT_CFG1[3:2] : 00 - High speed mode
BOOT_CFG1[1] : 0 - eMMC reset disable
BOOT_CFG1[0] : 0 - Throught the SD pad
BOOT_CFG2[7:5] : 101 - 4bit DDR
BOOT_CFG2[4:3] : 01 - USDHC-2
BOOT_CFG2[2] : 0 - Boot ROM default
BOOT_CFG2[1] : 0 - Boot acknowledge enable
BOOT_CFG2[0] : 0 - Use default values
MMC_DLL_DLY[6:0] : 0000000


Of case, I try to change BOOT_BUS_CONDITIONS [177] and



To boot eMMC with x4,x8 DDR in normal boot, need some more setting?


To see the eMMC bus signal log on ROM boot function,

I.MX6 output MMC_CMD and parameter based on the device boot flow in the IMX6DQRM Figure 8-11 and 8-16.

Switch command (CMD6) set PARTITION_CONFIG(0x01B34900), Hi-speed(0x03B9_0100) and BUS_WIDTH(0x03B70500) and eMMC respond with no error.

After send READ_MULTIPLE_BLOCK(CMD18) and read 512byte from sector 0,

i.MX6 stop MMC_CLK and no response any more.


Best regards,