[U-Boot-Users] Where in u-boot is the RAM "Mode Register"programmed?

Ulf Samuelsson ulf at atmel.com
Thu Mar 22 23:36:39 CET 2007

  ----- Original Message ----- 
  From: Bjook 
  To: u-boot-users at lists.sourceforge.net 
  Sent: Thursday, March 22, 2007 10:56 PM
  Subject: [U-Boot-Users] Where in u-boot is the RAM "Mode Register"programmed?


  My question is: Where in u-boot is the RAM "Mode Register" programmed?  Also, is my PCB usable with its mangled RAM address lines?


  I am using the "at91rm9200dk" configuration with a couple of changes.  

  I ran into problems with the RAM.  We are using a 64Mbit MT48LC2M32 instead of the 128Mbit MT48LC8M32 which should not be a problem.  Same chip except for half the capacity.

  The only problem is my hardware layout guy decided to mangle the address lines when he connected the RAM to the ARM processor.  His reasoning was that a RAM address is a RAM address is a RAM address.  If you always access the RAM from the Arm chip then the mangled lines will always get decoded and you will get the correct data value.


  What the layout guy did not realize was that this RAM has a Mode Register that needs to be programmed.  Where does this happen in u-boot?  If I can find out where it is set then I can decode the mangled address lines and put the proper value in.

  Also I will set the "burst read" to 0.



  Do you think this situation salvageable?  A10 is the same because it is a special line but I may need to jumper A8 and A9 since it looks like they are only used to program the address register.


  The mangled lines are as follows

  Normal -> Mangled

  A0 -> A1

  A1 -> A3

  A2 -> A2

  A3 -> A11

  A4 -> A7

  A5 -> A8

  A6 -> A6

  A7 -> A4

  A8 -> A9

  A9 -> A0

  A10 -> A10


  Next time I will fix the mangled lines but I really need to prove out my design on my current 50 boards since another spin takes around a month (because of BGA chips).



You need to know what flash memory you are using.
If you are using a dataflash, then it takes place in dataflashboot.bin, not in U-Boot.
Otherwise you have to look at the cpu/arm920t/at91rm9200 directory.
Should be an assembler file there. Dont remember its name.

Best Regards
Ulf Samuelsson 
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