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Omap35xx -> AM37xx Migration: Clock ?

Arno Steffens
Intellectual 930 points
Other Parts Discussed in Thread: AM3703

How to change the clock of the core from 600MHz to 1GHz? Is it done by xloader, uboot or kernel? Can you give some help where to find this?

Are there other software issues to take care?

I am using uboot 2010.10 and 2.6.33 kernel.

Thanks

  • 0
    TI__Expert 4590 points

    Arno Steffens (on linux-omap) said:

    Set CPU frequency one time at start would be ok for the beginning,
    just from 600MHz to 1GHz.
    I don't use dynamic scaling, this would be a later step maybe.
    I just want to migrate from one processor to the other. Is there a
    recommendation to use a newer kernel/uboot?
    In the AM datasheet I read L3 = 200 MHz, I am not sure about what
    frequency an Omap35xx is running.

    I'm feeling a bit lost to find the formula for the PLL in the around
    4000 page datasheet.


    To quickly get to 1GHz value, making changes to x-loader would be better. Corresponding settings are not changed in u-boot and linux kernel.

    For dynamic scaling, cpufreq needs to be enabled in the kernel configuration. (Changes to x-loader continue to be valid).

    BTW, are you using the PSP kernel release? or a different source base? Due to differences in the kernel revisions and patches, the recommendations may vary.

  • 0 in reply to Sanjeev Premi
    Intellectual 930 points

    From my expeirence the Uboot overwrites the clock settings, as I remember my tests changing the RAM clock.

    As I remember right this line in lowlevel_init.S in uboot is responsible for clock. Call me stupid, but I couldn't found in the 4000 sheets a formula calculating the clock out of this parameters: MPU_M_12_ES2, MPU_N_12_ES2, MPU_FSEL_12_ES2, MPU_M2_ES2

    mpu_dpll_param:
    /* 12MHz */
    /* ES1 */
    .word MPU_M_12_ES1, MPU_N_12_ES1, MPU_FSEL_12_ES1, MPU_M2_12_ES1
    /* ES2 */
    .word 0x0FA,0x04,0x07,0x01        // Running with a 13MHZ clock this is what we are using currently:
    /*
    .word MPU_M_12_ES2, MPU_N_12_ES2, MPU_FSEL_12_ES2, MPU_M2_ES2
    .word 0x0FA,0x05,0x07,0x01 500MHz
    .word 0x113,0x05,0x07,0x01 550MHz
    .word 0x0FA,0x04,0x07,0x01 600MHz
    */
    /* 3410 */
    .word MPU_M_12, MPU_N_12, MPU_FSEL_12, MPU_M2_12

    I am not using a PSP currently. What is the latest one you would recommend for AM3703? The latest I found is Sitara SDK 4.01(although I only could find a download link to 4.00.01), which seems to include PSP 03.00.01.06)  - a 2.6.32 system. The problem with this is, it is not supporting Micron NAND flash, what I am using.

     

     

     

  • 0 in reply to Arno Steffens
    TI__Expert 4590 points

    Functionality of u-boot does vary across distributions/releases. I may have to check - but usually the changes in x-loader carry-forward to u-boot as well.

    Clock settings are defined in the TRM section "Processor Clock Configurations" See "Table 3-59. Processor Clock Configurations" as well.

    Do note that clock change to 1GHz should also be supported by the change in the voltage corresponding to the OPP.

    The last PSP (x-loader, u-boot and Linux kernel) baseline v04.00.02.00.07 can be obtained from the Arago project area [http://arago-project.org/git/projects/]. Check the repos: x-load-omap3.git, u-boot-omap3.git and linux-omap3.git. The kernel version would be 2.6.37. Sitara SDK based on this baseline is in works.

     

  • 0 in reply to Sanjeev Premi
    Intellectual 930 points

    Thanks, I will check this versions. From what I understand in this setup uboot doesn't change clocks, it is all done in x-loader?