Yes, the two SD socket on iMX28 supports 8 bits mode on iMX28 EVK board.
static struct mxs_mmc_platform_data mmc0_data = {
...
.caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA
| MMC_CAP_DATA_DDR,
...
};
static struct mxs_mmc_platform_data mmc1_data = {
...
.caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA
| MMC_CAP_DATA_DDR,
...
};
Hi Pt, till SDIO 3.0 specification, there is only 4 bit SDIO mode, no 8 bit SDIO mode was defined. Only eMMC was defined for 8 bits mode, for iMX28, it can support 8 bits mode too.
Did MCIMX28EVK use 8-bit mode?
Yes, the two SD socket on iMX28 supports 8 bits mode on iMX28 EVK board.
static struct mxs_mmc_platform_data mmc0_data = {
...
.caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA
| MMC_CAP_DATA_DDR,
...
};
static struct mxs_mmc_platform_data mmc1_data = {
...
.caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA
| MMC_CAP_DATA_DDR,
...
};
Hi Qiang_FSL
Thank you. What is the advantage of 8 bit mode? For our customized board we are providing a sd card socket. is 4bit mode enough for that?
Regards
Pt
IMHO, I think that the main advantage of 8bit mode concern into the speed for data reading, as observed in the eMMC. The writting not suffer some speed-up as reading when use 8bits instead of 4bits.