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Registered: ‎10-30-2009

Help! Changing from RLDRAM to LPDDR for a PPC440

Hey all,


I currently have a working build of the kernel using an 128MB RLDRAM connected on the PLB bus.  I am trying to build the same kernel against a new DTS file with a 128MB LPDDR memory.


The only significant change (that I can see) is in the DTS file:



 160   lpddr: memory@0 {                                                               
 161     device_type = "memory";                                             
 162     reg = < 0x0 0x8000000 >;                                
 163   } ;                                                                  



 161   plb_if_wrapper_0: memory@0 {
 162     device_type = "memory";
 163     reg = < 0x0 0x8000000 >;
 164   } ;


I have written a small "memory test" program that I build through the tools and it runs successfully. 


Using XPS to generate a BSP I compare the drivers generated and the only difference that the RLDRAM has this driver: generic_v1_00_a and the LPDDR has this one: mpmc_v3_01_a.  I am unable to find any of the files (xmpmc.*) in the kernel source (from the git tree).  I can only assume that this hasn't made it into the releases?  I was wondering if anyone knew if there was a suitable driver, had patched this one above in, or had any ideas?


Any ideas would be great - I am going to look into getting this driver built into and used by the kernel.  Thanks sooo much in advance!!


EDIT:  I have a ml507 board I could try building for as well.

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Xilinx Employee
Xilinx Employee
Registered: ‎09-10-2008



You don't really say what the results of the problem are, is the kernel not building, not running?


I don't think that change that you made would be seen by the kernel, but I haven't dug in to verify that.


There really aren't drivers for the memory to my knowledge (or not remembering).  The kernel just looks for memory in the device tree.



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