IMX6UL Boot Issue

[jamesk1]

I have a IMX6UL loading Uboot from SPI flash, then booting Linux from SD. If I reboot Linux of preform a POR(Power-On-Reset) using the reset pin, the restart crashes after my first frame of data from the SPI flash. 

If I perform a POR while in uboot or before Linux has finished booting my reset works correctly.

Any ideas what is going on? 

Thanks

[igorpadykov]

Hi James

some components (including SPI flash) may be not reset with processor POR,

so recommended to reset power for whole board, as it is done on i.MX6UL EVK using U708 UM805

Schematics (1)
MCIMX6UL-EVK_DESIGNFILES
Design files, including hardware schematics, Gerbers, and OrCAD files. (REV 0)
http://www.nxp.com/products/sensors/gyroscopes/i.mx6ultralite-evaluation-kit:MCIMX6UL-EVK?fpsp=1&tab...

Best regards
igor
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[jamesk1]

Hi Igor

Thank you for your help. The Eval board method of power cycling the whole board is not a viable solution for us as this looses the ability to monitor the reset cause, so if the is a watchdog the reset cause will still display as a POR. 

I am curious if there are any work arounds without resetting flash,

I have narrowed the issue down to changing the flash from 3 byte address mode to a 4 byte address mode, so currently I am unable to access half my memory.

I could latch the watchdog powered from a different power rail or gate my power to the flash and buffer all my signal to prevent leakage into the flash device on power down, but these all seem quite extreme when all that is needed is a flash reset command.

 Thank for the help

James

[igorpadykov]

Hi James

one can try to send to spi nor reset command (check it in spi nor datasheet) and reset

ecspi module, described in sect.20.4.5 Reset i.MX6UL Reference Manual) before watchdog reset.

Best regards
igor