@abedong 在 A64求助大佬帮看看日志，进不去, 中说：
try card 2
[mmc]: mmc driver ver 2015-12-07 18:31:00
[mmc]: get sdc_ex_dly_used 2, use auto tuning sdly
[mmc]: current is product mode, it will tune sdly later
SUNXI SD/MMC: 2
[mmc]: start mmc_calibrate_delay_unit, don't access device...
[mmc]: delay chain cal done, sample: 200(ps)
[mmc]: delay chain cal done, ds: 200(ps)
[mmc]: Try SD card 2
[mmc]: mmc send if cond failed
[mmc]: send app cmd failed
[mmc]: Try MMC card 2
[mmc]: host caps: 0x6f
[mmc]: MID 000015 PSN 84708f1d
[mmc]: PNM 8GME4R -- 0x38-47-4d-45-34
[mmc]: PRV 0.1
[mmc]: MDT m-1 y-2018
[mmc]: MMC v5.1
[mmc]: speed mode : HSSDR52/SDR25
[mmc]: clock : 50000000 Hz
[mmc]: bus_width : 8 bit
[mmc]: user capacity : 7456 MB
[mmc]: boot capacity : 4096 KB
[mmc]: rpmb capacity : 512 KB
[mmc]: SD/MMC 2 init OK!!!
[mmc]: EOL Info(Rev blks): Urgent!!
[mmc]: Wear out(type A): Exceeded its max estimated life time
[mmc]: Wear out(type B): Exceeded its max estimated life time
[mmc]: gen_tuning_blk_bus8: total blk 10
[mmc]: gen_tuning_blk_bus4: total blk 6
[mmc]: write_tuning_try_freq: write ok
[mmc]: Pattern compare ok
[mmc]: Write tuning pattern ok
[mmc]: ================== start tuning HSSDR52_SDR25...
[mmc]: already at HSSDR52_SDR25 mode
[mmc]: skip current freq 400000
[mmc]: skip current freq 25000000
[mmc]: start tuning freq: 2-50000000
[mmc]: s0-255 e0-0 s1-0 e1-0
[mmc]: s0-255 e0-0 s1-0 e1-0
[mmc]: s0-0 e0-4 s1-255 e1-0
[mmc]: ================== start tuning HSDDR52_DDR50...
[mmc]: already at HSSDR52_SDR25 mode
[mmc]: mmc switch failed
[mmc]: mmc swtich status error
[mmc]: mmc switch bus width failed
[mmc]: switch bus width fail
[mmc]: switch to HSDDR52/DDR50 fail
[mmc]: tuning fail at HSDDR52_DDR50
[mmc]: already at HSSDR52_SDR25 mode
[mmc]: mmc switch failed
[mmc]: mmc swtich status error
[mmc]: mmc switch bus width failed
[mmc]: switch bus width fail
[mmc]: switch back to HSSDR52_SDR25 8bit fail
[mmc]: bus tuning fail, err -6
[mmc]: mmc_init: mmc init fail, err -6
检查eMMC