[pingequalab]

Note: Follow-up PR #3092 submits the companion single-sector write (CMD24) busy-wait and 2x 0xFF sdWait() idle check in lib/HAL/sd_card/sd_diskio.cpp.

Summary

Fixes an unrecoverable SPI SD card zombie state after any transient read/command timeout, clocks a trailing 0xFF byte on CS deassertion so the SD card releases MISO on shared SPI buses, and fixes USBSerial::vprintf printing va_list stack pointers on CLI commands such as storage free sd.

Hardware Tested

• Board: m5stack-sticks3 (v1.17 / 2b6ba4d) with external shared-SPI module (CC1101 + NRF24 + 32GB MicroSD sharing SCK=5, MISO=4, MOSI=6).
• Applies to all SPI SD targets using lib/HAL/sd_card and USB-serial CLI targets using USBSerial.

Changes (fefc13b)

• src/core/sd_functions.cpp: Call closeSdCard() and displayError("SD Read/Mount Error", true) when the second fs.exists(rootPath) fails for SD, resetting _pdrv to 0xFF so the next setupSdCard() performs a real SPI re-initialization (160 SCK + CMD0).
• lib/HAL/sd_card/sd_diskio.cpp: Clock one trailing 0xFF byte after pulling ssPin HIGH in sdDeselectCard() so the card releases DAT0/MISO to Hi-Z on shared SPI buses.
• src/core/serial_commands/storage_commands.cpp: Unmount via closeSdCard() and report an error if SD.totalBytes() == 0, and guard freeBytes against unsigned underflow.
• src/core/USBSerial/USBSerial.h: Forward va_list to out->vprintf(fmt, args) instead of out->printf(fmt, args).

Verification

• Build: pio run -e m5stack-sticks3 -> SUCCESS.
• On-device verification: storage free sd accurately formats 64-bit capacities (31702614016 Bytes on 32GB MicroSD), and 10 rounds of CC1101 / NRF24 / SD Card switching confirm hot-remount recovery without ESP.restart().