imx6ul emmc 8bit mode，boot fail

[chunqiaohe]

Hi all,

     i have a project , the cpu is imx6ul.   my hardware board 's boot device is EMMC.  i use the plull_up/pull_down resistor to set EMMC 8bit mode (Boot_cfg2[7~5]=110) , then i build my u-boot, zImage and dtb. i use the mfgtool download firmware to my board. all are ok , there is on error happen .  during the downloading , i measured the imx6ul's SDHC2 cmd,clk,d0-d7 all ok . the debug serial have normal log info.

    but after the download, i power on my board ,but the system cann't boot up, the debug serial haven't any info.

finally , i try to change the hardware emmc setting to 1 bit mode ((Boot_cfg2[7~5]=000). then i power on my board, the system can boot up.,the debug serial have booting log . all the function is ok .

    i don't know , why i use 8bit mode to down firmware is successful, i measured the D0-D7 data line are ok , but 

i can't boot up with 8bit mode EMMC.  how to change?   is my u-boot issue? 

   thanks!

[lemficb]

Hi chunqiao,

      I have the same issue with you. I can also boot up with 1 bit mode, but when I set 8 bit mode ,there is nothing on my debug serial. Can you tell me the method  how  to solve this problem ? This problem have troubled me for a long time.

I am looking forward to your reply.

     Best regards

      Link

[igorpadykov]

Hi chunqiao

in general one can try 4 bit mode. Then check with

oscilloscope all emmc lines, where it fails comparing with good

case. Also one can debug it with jtag using procedure described on

https://community.nxp.com/thread/301056#303710 

Best regards
igor
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[chunqiaohe]

Hi igorpadykov,

    thanks for your quick replay. i already try to modify hardware boot_cfg to 4bit mode.  but also the mfgtool download ok ,but cann't bootup. 

    in 8bit emmc mode. i measured all the emmc line, during downloading , the emmc_clk is 50MHz, D0-D7 have data wave .

when download finished, i power on my board,  i test the emmc_clk is 20MHz, at the same time , only D0 line have data wave,D2-D7 lines are no data wave.   so the system no bootup, the serial havn't any log information.

   sorry , i design my board without  JTAG PIN reserved.

   how do i check my design?  the firmware look like no problem , because i only change the hardware boot_cfg to 1bit, system can boot up , all function is ok.  if the hardware's issue, i checked the boot_cfg pins setting are right.  

  thanks!

[igorpadykov · Accepted solution]

I do not think that it is possible to debug such issues without jtag.

Best regards
igor

[chunqiaohe]

Hi igorpadykov,

     would you please give some advice?  without jtag, how to try to debug?

     thanks!