I have verified this on 4 Jetson Nano modules (2 with SD Card and 2 with eMMC). The rootfs and Image are identical on all 4 modules. The device tree has a small modification for the SD Card vs eMMC (see attached file).
devicetree_diff.txt (473 Bytes)
The u-boot finds a spi flash “mx25u3235f” on the Jetson Nano with SD Card. And u-boot fails to find the spi flash on the Jetson Nano with eMMC. The scope shows no activity on the spi0 pins on the Jetson Nano with eMMC. Attached are the u-boot log, sysfs pinmux settings, and gpio settings for both. The ksz8795-switch uses the spi driver to read/write registers, and when it fails the chip IDs are all zero.
spi0-pass-sdcard.txt (9.2 KB)
spi0-fails-emmc.txt (8.6 KB)
Command used to flash the SD Card module:
sudo ./flash.sh jetson-nano-devkit mmcblk0p1
Command used to flash the eMMC module:
sudo ./flash.sh jetson-nano-emmc mmcblk0p1