Hi,
I setup CoreELEC on my Odroid N2+
CoreELEC (community): 20.3-Nexus_devel_20230929234029 (Amlogic-ng.arm)
Machine model: Hardkernel ODROID-N2Plus
CoreELEC dt-id: g12b_s922x_odroid_n2plus
Amlogic dt-id: g12b_w400_b
emmc is uses für CoreELEC System, want to use microSD for data.
I figured pure data transfer rates with actually fast SanDisk Extreme PRO card 
/dev/mmcblk1p1 got xfs file system
# dmesg | grep mmc
[ 0.000000@0]d meson_g12a_sdemmc_init: register amlogic sdemmc clk
[ 0.000000@0]d meson_g12a_sdemmc_init: register amlogic sdemmc clk
[ 0.788618@3]- meson-mmc: mmc driver version: 3.02, 2017-05-15: New Emmc Host Controller
[ 0.826746@3]- meson-mmc: meson_mmc_probe() : success!
[ 0.836939@4]- meson-mmc: gpio_cd = 1ca
[ 0.878747@4]- meson-mmc: meson_mmc_probe() : success!
[ 1.046123@3]- meson-mmc: emmc: clk 199999997 tuning start
[ 1.049070@3]- meson-mmc: emmc: adj_win: < 0 2 3 4 >
[ 1.049073@3]- meson-mmc: step:4, delay1:0x4104104, delay2:0x4004104
[ 1.051979@3]- meson-mmc: emmc: adj_win: < 0 2 3 4 >
[ 1.051981@3]- meson-mmc: step:8, delay1:0x8208208, delay2:0x8008208
[ 1.054887@3]- meson-mmc: emmc: adj_win: < 0 2 3 4 >
[ 1.054888@3]- meson-mmc: step:12, delay1:0xc30c30c, delay2:0xc00c30c
[ 1.057731@3]- meson-mmc: emmc: adj_win: < 0 2 3 4 >
[ 1.057733@3]- meson-mmc: step:16, delay1:0x10410410, delay2:0x10010410
[ 1.059920@3]- meson-mmc: emmc: adj_win: < 0 3 4 >
[ 1.059922@3]- meson-mmc: left:3, right:0, mid:4, size:4
[ 1.059923@3]- meson-mmc: step:0, delay1:0x0, delay2:0x0
[ 1.059926@3]- meson-mmc: emmc: sd_emmc_regs->gclock=0x10000245,sd_emmc_regs->gadjust=0x42000
[ 1.059997@3]- emmc: new HS200 MMC card at address 0001
[ 1.059998@3]- emmc: clock 199999997, 8-bit-bus-width
[ 1.060355@3]- mmcblk0: emmc:0001 CJTD4R 58.2 GiB
[ 1.060517@3]- mmcblk0boot0: emmc:0001 CJTD4R partition 1 4.00 MiB
[ 1.060637@3]- mmcblk0boot1: emmc:0001 CJTD4R partition 2 4.00 MiB
[ 1.060757@3]- mmcblk0rpmb: emmc:0001 CJTD4R partition 3 4.00 MiB
[ 1.061309@3]- mmcblk0: p1 p2
[ 1.082743@4]- meson-mmc: card IN
[ 1.186301@4]- meson-mmc: normal card in
[ 1.413168@4]- mmcblk1: sd:aaaa SR01T 954 GiB
[ 1.418228@4]- mmcblk1: p1
[ 1.705719@1]- init: ### /dev/mmcblk0p1: 84 files, 40621/65501 clusters
[ 1.824998@0]- EXT4-fs (mmcblk0p2): couldn't mount as ext3 due to feature incompatibilities
[ 1.825225@0]- EXT4-fs (mmcblk0p2): couldn't mount as ext2 due to feature incompatibilities
[ 1.917611@2]- EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 4.174726@4]- meson-mmc: Error: sdio_host is NULL
[ 4.174731@4]- meson-mmc: [sdio_reinit] finish
[ 4.992143@2]- XFS (mmcblk1p1): EXPERIMENTAL reflink feature enabled. Use at your own risk!
[ 4.992487@2]- XFS (mmcblk1p1): Mounting V5 Filesystem
[ 5.196979@1]- XFS (mmcblk1p1): Ending clean mount
# cat /sys/kernel/debug/sd/ios
clock: 50000000 Hz
actual clock: 50000000 Hz
vdd: 21 (3.3 ~ 3.4 V)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 2 (on)
bus width: 2 (4 bits)
timing spec: 2 (sd high-speed)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)
How do I set sd uhs SDR104 mode?
thx
Rossi