Rock64 v3 and SD-Cards

[ketominer]

From what I've heard, the issue is that GPIO0_D6 (SDMMC0_PWREN) is left floating by current Linux devicetree configurations, but needs to be set to high or low in order to select an appropriate SDCard voltage.

You can solder a connection between test pad 2302 and 3.3v to revert your Rev3 board's SD-Card slot to Rev2 behavior, which should work with all cards.
If you have a UHS-capable MicroSD card, you can solder a connection between test pad 2303 and ground to force the slot into UHS mode.

Edit: The test pad can be located on the back of the PCB, near the center. I've highlighted it in this drawing, in red: https://i.imgur.com/F9BCSkj.png

It works! I couldn't get it to work connecting it to 3.3V (I'm using UHS cards) but only to ground.