Help with u-boot when using the eMMC card in DDR mode

[Abder]

Hi,

I have been trying recently to optimize the boot time on a customized board
based on the IMX6DP.

For the time being, I succeeded in enabling the DDR (dual data rate) mode
for the emmc to speed up the data rate for read and write cycles in u-boot.

By reading a file from the emmc using the "load" command (e.g. load mmc 2:1
0x12000000 file), I can see that the data rate has doubled, confirming that
the DDR mode is enabled.

However, the problem I have is that when I execute the u-boot command "mmc
dev 2" to switch the current device to the onboard eMMC, the command fails
with the output below : (with DEBUG enabled)

U-Boot >mmc dev 2
blk_find_device: if_type=6, devnum=2: usdhc at 02198000.blk, 6, 2
ofnode_read_u32: vmmc-supply: 0x33 (51)
ofnode_read_u32: vqmmc-supply: 0x33 (51)
clock is disabled (0Hz)
fixed_regulator_set_enable: dev='3p3v', enable=1, delay=0, has_gpio=0
clock is enabled (400000Hz)
Command failed, result=1
U-Boot >

and after this command, any attempt to interact with the emmc (e.g. fatls
mmc 2:1 ) ends with failure.

To enable the DDR mode, all I did was define the macro
CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE in the header of my board.

Any help is greatly appreciated !

--

Abder,