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New dm8148 silicon revision causes problems with u-boot & DDR3

Joel Keller
Expert 1305 points

Hi,


We recently recieved a new spin of our board that happened to have an updated silicon revision for the DM8148.  Bootloader prompt was not showing up.  After debugging for a while, I discovered that u-boot was taking the "DDR2 codepath" instead of the "DDR3 codepath", because the get_cpu_rev() function in u-boot's sys_info.c was now returning "PG1_0" instead of "PG2_1".  This occured because the silicon revision read from the DEVICE_ID register is now 0x4 instead of 0x3.

An easy fix, is to map rev 0x4 to PG2_1 in the get_cpu_rev() function, which works for me.  

A silly question though:  What does PG stand for?  I see PG3.0 referenced here http://e2e.ti.com/support/embedded/linux/f/354/t/220849.aspx  Is it mearly different versions of the EVM kit?

  • 0
    TI__Genius 15310 points

    Hi Joel,

    PG is a device revision.  Our latest revision for DM8148 is PG3.  Do you download the latest EZSDK, 5.05, to use with it?  The device ID in uboot and kernel need to be update to be able to boot.

    BR,

    Viet

  • 0 in reply to Viet Dinh
    Expert 1305 points

    Hi Viet,

    So, PG2_1 vs PG1_0 vx PG3 are these different 'device revisions' of the DM8148 SOC, or the EVM board, or some other 'device'?  

    We are currently using EZSDK 5.03, because EZSDK 5.04 had some problems for us, and it takes some development effort for us to upgrade EZSDK versions as we have had to make numerous customizations.  Perhaps we should try to move to 5.05 though.  Can you tell me what specifically needs to be changed in the linux kernel for PG3?

    Thanks,

    Joel

  • 0 in reply to Joel Keller
    TI__Genius 15310 points

    Hi Joel,

    You are right, it is different in "device revision" of DM8148, not EVM or other device.

    You can see the patch and changed for PG3 from this E2E post:  http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/222257.aspx?Redirected=true.  Please note that they are using 5.04 so I don't know if it is apply to your 5.03 or not.

    BR,

    Viet

  • 0 in reply to Viet Dinh
    Expert 1305 points

    Excellent.  Thanks Viet, that link is very helpful for me!