VisionFive 2 — SD card (mmc1) fails "voltage select" / "Error reading cluster" in U-Boot v2026.07

[Milad]

Board: StarFive VisionFive 2, revision v1.3B, 8GiB RAM variant
Boot mode: SPI NOR U-Boot (recommended/supported mode, not the deprecated
BootROM direct-boot)

U-Boot version: v2026.07 final release, self-built on-board (native RISC-V
build) from the official u-boot-2026.07.tar.bz2 tarball + OpenSBI v1.7,
built Jul 10 2026 with gcc 15.3.0 / GNU ld 2.46.50.20260617

Issue:
SD card (mmc1) fails to initialize in U-Boot. Full serial output:

Card did not respond to voltage select! : -110
** Booting bootflow '<NULL>' with efi_mgr
Loading Boot0000 'usb 0' failed
Error reading cluster
Loading Boot0001 'mmc 1' failed
EFI boot manager: Cannot load any image
Boot failed (err=-14)
Card did not respond to voltage select! : -110
Card did not respond to voltage select! : -110
Card did not respond to voltage select! : -110
Card did not respond to voltage select! : -110

Isolation steps taken:
- Reproduced identically on two different SD cards: a Samsung Pro Plus
128GB (UHS-I) and an Apacer 16GB R85 (SDHC, non-UHS)
- Confirmed the cards, SD slot, and filesystem contents are all healthy:
booted the Debian installer's Linux environment from USB, and it detects
and cleanly mounts the same SD card's partitions (mmcblk1, mmcblk1p1-3),
with valid EFI files present at correct sizes (BOOTRISCV64.EFI and
grubriscv64.efi, ~156KB each)
- Running `mmc info` directly at the U-Boot prompt fails outright with the
same -110 error, before any filesystem access is attempted
- Installing the same Debian image to a USB mass storage drive instead of
SD works perfectly — boots and installs with no issues, confirming the
failure is isolated specifically to the MMC/SD driver path
- Also reproduced on a v2026.07-rc4 build with an identical failure, so
this is not limited to a release candidate — it persists in the final
v2026.07 release
- Have not tested eMMC (don't have a card on hand)

Expected behavior:
SD card should initialize and boot normally. Booting via SPI-loaded U-Boot
reading SD/eMMC as normal storage is the standard supported path on this
board — only direct BootROM SD/eMMC boot (bypassing SPI U-Boot entirely) is
documented as deprecated, which is not what's being used here.

Happy to provide more logs, test patches, or do further research if useful.

Thanks,
M.H.