1GB ddr3l twin die only work with 800MB

[jochenstehle]

Hello,

we use an i.mx6ul on our custom board. till now we used a 512MB micron chip. now we changed to the MT41K512M16VRN-107 IT:P. It is a twin die chip with only one CS. But wenn u-boot calculate the memory automaticly it shows correct 1GB but the kernel didnt start. Kernel hangs after:

Starting kernel ...

Uncompressing ........ done, booting the kernel.

When we set the memory fix to 800MB it worked fine.

Where is here the problem?

We think something in uboot isnt correct? 

[Yuri]

Hello,

  Please check memory and its settings, using the Stress test.

i.MX6/7 DDR Stress Test Tool V3.00  

  Also, use recommendations of U-boot porting in "i.MX_Porting_Guide.pdf".

Have a great day,
Yuri

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[jochenstehle]

Hello Yuri,

our schematic was validatet by micron and seems to be correct.

   -We used the stress tester tool. this one with GUI worked fine and we was able to run calibration(see the log in the attachement). An read/write to a spezific adresses with the command on the right side of the gui window worked correct. Also the stress test in the tool worked. see below and the attached log. the init script for the tool is also attached --> 1gbtest.inc

   

-stress tester startet from u-boot dont work on our 1GB board, but on the exact same board only with 512MB ram it work. i think this is maybe because of the wrong imximage.cfg(see the attachment)???

at this point it hangs.

- If we pass in the u-boot code a fixed dram size with 800MB the system booted up correctly (if we pass bigger size e.g. 850MB kernel dont start). If u-boot calculate the value itself the kernel dont start because it than take the values again from the imximage.cfg

But the imximage.cfg could not be completly wrong because as we said if we limit the DRAM to 800MB the system start and in Linux we are able to use these 800MB ram correctly.

in the excel we use these values:

Thank you very much.

Jochen

[Yuri]

Hello,

   please check PCB design, in particular DDR address lines, using rules in

the  Hardware Development Guide.

http://cache.nxp.com/files/32bit/doc/user_guide/IMX6ULHDG.pdf 

Regards,

Yuri.