i.MX 93 BSP Manual PD24.1.1 Documentation Rev.: imx8mp-pd22.1.2-51-ga548be7d
Warning
These kinds of devices are hot-pluggable. Nevertheless, you must ensure not to unplug the device while
it is still mounted. This may result in data loss!
After inserting an SD/MMC card, the kernel will generate new device nodes in /dev. The full device can be
reached via its /dev/mmcblk1 device node. SD/MMC card partitions will show up as:
/dev/mmcblk1p<Y>
<Y> counts as the partition number starting from 1 to the max count of partitions on this device. The
partitions can be formatted with any kind of le system and also handled in a standard manner, e.g. the
mount and umount command work as expected.
Tip
These partition device nodes will only be available if the card contains a valid partition table (”hard disk”
like handling). If no partition table is present, the whole device can be used as a le system (”oppy”
like handling). In this case, /dev/mmcblk1 must be used for formatting and mounting. The cards are
always mounted as being writable.
DT conguration for the MMC (SD card slot) interface can be found here: https://git.phytec.de/
linux-imx/tree/arch/arm64/boot/dts/freescale/imx93-phyboard-segin.dts?h=v6.1.55_2.2.0-phy3#n216 or
here: https://git.phytec.de/linux-imx/tree/arch/arm64/boot/dts/freescale/imx93-phyboard-nash.dts?h=
v6.1.55_2.2.0-phy3#n201
DT conguration for the eMMC interface can be found here: https://git.phytec.de/linux-imx/tree/arch/
arm64/boot/dts/freescale/imx93-phycore-som.dtsi?h=v6.1.55_2.2.0-phy3#n194 or here:
7.4 eMMC Devices
PHYTEC modules like phyCORE-i.MX 93 is populated with an eMMC memory chip as the main storage.
eMMC devices contain raw Multi-Level Cells (MLC) or Triple-Level Cells (TLC) combined with a memory
controller that handles ECC and wear leveling. They are connected via an SD/MMC interface to the i.MX
93 and are represented as block devices in the Linux kernel like SD cards, ash drives, or hard disks.
The electric and protocol specications are provided by JEDEC (https://www.jedec.org/
standards-documents/technology-focus-areas/flash-memory-ssds-ufs-emmc/e-mmc). The eMMC man-
ufacturer’s datasheet is relatively short and meant to be read together with the supported version of the
JEDEC eMMC standard.
PHYTEC currently utilizes the eMMC chips with JEDEC Version 5.0 and 5.1
7.4.1 Extended CSD Register
eMMC devices have an extensive amount of extra information and settings that are available via the Extended
CSD registers. For a detailed list of the registers, see manufacturer datasheets and the JEDEC standard.
In the Linux user space, you can query the registers:
target:~$ mmc extcsd read /dev/mmcblk0
You will see:
Accessing Peripherals 48
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