topic System hang when using devmem2 to read GPMI registers in i.MX Processors

System hang when using devmem2 to read GPMI registers

abutter — Wed, 21 Nov 2018 04:12:02 GMT

When running devmem2 0x01806000 w to check GPMI registers, the system seemed hang, there is no response when I input something on serial console.

I tried other register, devmem2 works and I could read 0x01806000 in u-boot using md command:

root@imx6ul-var-dart:~# devmem2 0x020c4068 w
/dev/mem opened.
Memory mapped at address 0x76f5e000.
Read at address 0x020C4068 (0x76f5e068): 0xC0C00F0F
root@imx6ul-var-dart:~# devmem2 0x01806000 w
/dev/mem opened.

I suspect if the clock for GPMI is disabled, but before reading the GPMI register, I run nandtest command, no crash or hang was seen.

Any suggestion is appreciated.

Thanks.

Re: System hang when using devmem2 to read GPMI registers

igorpadykov — Wed, 21 Nov 2018 23:31:27 GMT

Hi abutter

one can look at similar problem on below link, check register with memtool

Unable to access I.MX6ULL memory map registers using devmem2 - fsl-yocto-L4.9.11_1.0.0.tar

Best regards
igor
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Re: System hang when using devmem2 to read GPMI registers

abutter — Thu, 22 Nov 2018 04:48:03 GMT

memtool also cause hang. I would try on other board to check if it is caused by the NAND and its driver.

I also thought it would be because of disabled clocked, I would try to the registers later.