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Self-Refresh w/256MB of RAM in PM lowest power modes

Chris Read
Genius 3345 points

Has the self refresh mode for the LPDDR been tested with the full 256MB that's in the newer beagleboards and EVMs?

I know that both newer beagleboards and the OMAP-35x EVMs (e.g. Rev.G) have 256 MB of LPDDR on them.  Their POP packages use two LPDDR chips that are each 128MB to create the 256MB in the POP package.

My testing with PM indicate that when mem=99M kernel command-line parameter the system sleeps fine, and wakes up properly after sleeping for several minutes.  If I use the mem=99M@0x80000000 mem=128M@0x88000000 parameters that are suggested in the user guide for 256MB memory, then it doesn't wake up.

Any suggestions for getting self-refresh to work for 256MB?

 

Thanks,

 

Chris

  • 0
    Genius 3345 points

    I have looked through the Linux kernel email traffic on this and there were some patches about a year ago--some targeting the beagle board, but they don't seem to have filtered into the OMAP 3 EVM (particularly the Rev.G).  I have tried applying them to the EVM, but without success.

    Has the PSP been tested to make sure it can sleep for at least 2 minutes with all 256MB, i.e. both LPDDR chips in the POP package?

     

    Any other suggestions?

     

    Thanks,


    Chris

  • 0 in reply to Chris Read
    Genius 3345 points

    I was finally able to get it to work!

    I had to pass the LPDDR parameters to CS1 in addition to CS0 in the call to omap2_init_common_hw().

    I also had to set the muxing correctly for sdrc_cke1.  I tried doing it the way it was done in the beagle board's code, but it apparently didn't work.  I fixed it in U-Boot and that's what made the difference.

    - Chris

  • 0 in reply to Chris Read
    Genius 3345 points

    I also had to change to DDR_STACKED from DDR_DISCRETE in the board/ti/evm/evm.h file.