AnsweredAssumed Answered

EMMC drive not reliable

Question asked by David XY Zhou on Apr 4, 2018
Latest reply on Apr 24, 2019 by Robert Chapin



I have imx6ul dev board and Linux 4.15 yocto


Originally, we have 4G EMMC chip on dev board, occasionally it shows errors during initialization stage:


Now we have  8G EMMC (micro Electronics) ship on production boards. The EMMC drive is not reliable at all.

it sends out many errors:

blk_update_request: I/O error, dev mmcblk1, sector 2048

mmcblk1: error -84 transferring data, sector 14941960, nr 120, cmd response 0x900, card status 0xb00


Here is the setup to the chip:

clock:          50000000 Hz                                                     
actual clock:   49500000 Hz                                                     
vdd:            21 (3.3 ~ 3.4 V)                                                
bus mode:       2 (push-pull)                                                   
chip select:    0 (don't care)                                                  
power mode:     2 (on)                                                          
bus width:      3 (8 bits)                                                      
timing spec:    8 (mmc DDR52)                                                   
signal voltage: 0 (3.30 V)


Here is the device tree configuration:


pinctrl-assert-gpios = <&gpio5 1 GPIO_ACTIVE_HIGH>;
pinctrl-0 = <&pinctrl_usdhc2_8databits>;
pinctrl-names = "default";
fsl,delay-line = <0>;
max-frequency = <50000000>;
bus-width = <8>;


What else is missing?

Any suggestions?


Thank you,


David Zhou