➜ ~ dmesg| grep mmc
[ 1.926019] mmc0: SDHCI controller on fe2e0000.mmc [fe2e0000.mmc] using ADMA
[ 2.026282] mmc0: new HS400 Enhanced strobe MMC card at address 0001
[ 2.031712] mmcblk0: mmc0:0001 A3A444 230 GiB
[ 2.037074] mmcblk0: p1
[ 2.038122] mmcblk0boot0: mmc0:0001 A3A444 4.00 MiB
[ 2.040301] mmcblk0boot1: mmc0:0001 A3A444 4.00 MiB
[ 2.042564] mmcblk0rpmb: mmc0:0001 A3A444 4.00 MiB, chardev (243:0)
[ 2.150020] dwmmc_rockchip fe2c0000.mmc: IDMAC supports 32-bit address mode.
[ 2.150727] dwmmc_rockchip fe2c0000.mmc: Using internal DMA controller.
[ 2.155343] dwmmc_rockchip fe2c0000.mmc: Version ID is 270a
[ 2.155854] dwmmc_rockchip fe2c0000.mmc: DW MMC controller at irq 98,32 bit host data width,256 deep fifo
[ 2.156969] dwmmc_rockchip fe2c0000.mmc: Got CD GPIO
[ 2.169374] mmc_host mmc1: Bus speed (slot 0) = 400000Hz (slot req 400000Hz, actual 400000HZ div = 0)
[ 2.432912] mmc_host mmc1: Bus speed (slot 0) = 198000000Hz (slot req 200000000Hz, actual 198000000HZ div = 0)
[ 2.714811] dwmmc_rockchip fe2c0000.mmc: Successfully tuned phase to 230
[ 2.717703] mmc1: new UHS-I speed SDR104 SDXC card at address 544c
[ 2.719268] mmcblk1: mmc1:544c LX64G 58.9 GiB
[ 2.721418] mmcblk1: p1 p2
[ 5.394333] EXT4-fs (mmcblk1p2): mounted filesystem 00560a2f-4a48-4f42-85db-f7197f411193 ro with ordered data mode. Quota mode: none.
[ 8.122124] EXT4-fs (mmcblk1p2): re-mounted 00560a2f-4a48-4f42-85db-f7197f411193 r/w. Quota mode: none.
➜ ~ uname -a
Linux t6.superkali.lan 6.14.4-edge-rockchip64 #1 SMP PREEMPT Fri Apr 25 08:51:21 UTC 2025 aarch64 GNU/Linux
root@t6-2:~# dmesg | grep mmc
[ 1.793233] mmc0: SDHCI controller on fe2e0000.mmc [fe2e0000.mmc] using ADMA
[ 1.892860] mmc0: new HS400 Enhanced strobe MMC card at address 0001
[ 1.893418] mmcblk0: mmc0:0001 A3A444 230 GiB
[ 1.900752] mmcblk0: p1
[ 1.901187] mmcblk0boot0: mmc0:0001 A3A444 4.00 MiB
[ 1.902094] mmcblk0boot1: mmc0:0001 A3A444 4.00 MiB
[ 1.903152] mmcblk0rpmb: mmc0:0001 A3A444 4.00 MiB, chardev (243:0)
[ 2.015519] dwmmc_rockchip fe2c0000.mmc: IDMAC supports 32-bit address mode.
[ 2.015588] dwmmc_rockchip fe2c0000.mmc: Using internal DMA controller.
[ 2.015603] dwmmc_rockchip fe2c0000.mmc: Version ID is 270a
[ 2.015721] dwmmc_rockchip fe2c0000.mmc: DW MMC controller at irq 98,32 bit host data width,256 deep fifo
[ 2.016264] dwmmc_rockchip fe2c0000.mmc: Got CD GPIO
[ 2.029321] mmc_host mmc1: Bus speed (slot 0) = 400000Hz (slot req 400000Hz, actual 400000HZ div = 0)
[ 2.270630] mmc_host mmc1: Bus speed (slot 0) = 198000000Hz (slot req 200000000Hz, actual 198000000HZ div = 0)
[ 2.473628] dwmmc_rockchip fe2c0000.mmc: Successfully tuned phase to 247
[ 2.477145] mmc1: new UHS-I speed SDR104 SDXC card at address 544c
[ 2.478144] mmcblk1: mmc1:544c LX64G 58.9 GiB
[ 2.483356] mmcblk1: p1
[ 3.176039] EXT4-fs (mmcblk1p1): mounted filesystem 3aa41aca-1f77-4222-b253-8d444c3dfca5 ro with writeback data mode. Quota mode: none.
[ 8.484634] EXT4-fs (mmcblk1p1): re-mounted 3aa41aca-1f77-4222-b253-8d444c3dfca5 r/w. Quota mode: none.
root@t6-2:~# uname -a
Linux t6-2.superkali.lan 6.14.4-edge-rockchip64 #1 SMP PREEMPT Fri Apr 25 08:51:21 UTC 2025 aarch64 GNU/Linux
root@nanopct6-lts:~# dmesg | grep mmc
[ 4.386835] dwmmc_rockchip fe2c0000.mmc: No normal pinctrl state
[ 4.386849] dwmmc_rockchip fe2c0000.mmc: No idle pinctrl state
[ 4.386921] dwmmc_rockchip fe2c0000.mmc: IDMAC supports 32-bit address mode.
[ 4.386972] dwmmc_rockchip fe2c0000.mmc: Using internal DMA controller.
[ 4.386986] dwmmc_rockchip fe2c0000.mmc: Version ID is 270a
[ 4.387034] dwmmc_rockchip fe2c0000.mmc: DW MMC controller at irq 157,32 bit host data width,256 deep fifo
[ 4.387131] dwmmc_rockchip fe2c0000.mmc: Looking up vmmc-supply from device tree
[ 4.387431] dwmmc_rockchip fe2c0000.mmc: Looking up vqmmc-supply from device tree
[ 4.403026] mmc_host mmc1: Bus speed (slot 0) = 400000Hz (slot req 400000Hz, actual 400000HZ div = 0)
[ 4.495259] mmc0: Command Queue Engine enabled
[ 4.495299] mmc0: new HS400 Enhanced strobe MMC card at address 0001
[ 4.496710] mmcblk0: mmc0:0001 A3A561 57.6 GiB
[ 4.505219] mmcblk0: p1
[ 4.505766] mmcblk0boot0: mmc0:0001 A3A561 4.00 MiB
[ 4.506882] mmcblk0boot1: mmc0:0001 A3A561 4.00 MiB
[ 4.507923] mmcblk0rpmb: mmc0:0001 A3A561 16.0 MiB, chardev (234:0)
root@nanopct6-lts:~# uname -a
Linux nanopct6-lts 6.1.84-vendor-rk35xx #1 SMP Wed Dec 18 05:56:40 UTC 2024 aarch64 GNU/Linux
root@nanopct6-lts:~#
The first two are the variants with 256GB of eMMC, therefore non-LTS, while the last one is the LTS variant with 64GB of eMMC. From my tests with both the edge version and the vendor kernel, both negotiate in HS400 without any problems:
A test carried out by T6-2:
/dev/mmcblk0p1:
Timing cached reads: 7686 MB in 2.00 seconds = 3845.97 MB/sec
Timing buffered disk reads: 854 MB in 3.00 seconds = 284.38 MB/sec
I don't see your errors, so I think there might be something strange with your board. Can you try the edge kernel and tell me if you have the same problems, or the vendor kernel?