Solution of mmcblk0: error-84


Today, when reading and writing on the SD card of the prototype, the kernel reported an error:

mmcblk:0 error -84 transferring data, sector 8057, nr 1, cmd response 0x900, card status 0x0
sblk_update_request: I/O error, dev mmcblk0, sector 8057
Buffer I/O erron on dev mmcblk0p1, logical block 6009, lost ysnc page write

Start to check the data on the Internet, and summarize as follows:

Solution of mmcblk0: error-84


Solution of mmcblk0: error-84

It can be seen that all the solutions point to a problem, and the clock frequency of the device tree (DT) is not consistent with the actual clock frequency of the prototype. According to this clue, we found that it was a resistance error on the prototype hardware CLK that caused the CLK clock frequency to drop.