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How to enable dvfs in omap.

Thalib
Intellectual 580 points

Hi all,

I am using omap 2.6.37 running overo board. I have enabled the following option in the kernel menunconfig,


CPU Power Management --->
│ │ [*] CPU Frequency scaling
│ │ [ ] Enable CPUfreq debugging
│ │ <*> CPU frequency translation statistics
│ │ [*] CPU frequency translation statistics details
│ │ Default CPUFreq governor (ondemand) --->
│ │ -*- 'performance' governor
│ │ <M> 'powersave' governor
│ │ <*> 'userspace' governor for userspace frequency scaling
│ │ -*- 'ondemand' cpufreq policy governor
│ │ <*> 'conservative' cpufreq governor
│ │ [ ] CPU idle PM support


but still I could find the sys and entry in /sys/devices/system/cpu/cpufreq/ directory. Could some one help me to enable DVFS.

root@overo:/sys/devices/system/cpu# ls
cpu0 kernel_max online possible
cpufreq offline perf_events present
root@overo:/sys/devices/system/cpu# cd cpu0/
root@overo:/sys/devices/system/cpu/cpu0# ls
crash_notes
root@overo:/sys/devices/system/cpu/cpu0# cd ..
root@overo:/sys/devices/system/cpu# cd cpufreq/
root@overo:/sys/devices/system/cpu/cpufreq# ls
root@overo:/sys/devices/system/cpu/cpufreq#
-- 
Regards,
Mohamed Thalib H

  • 0
    TI__Expert 4590 points

    You must be using the mainline kernel as there is no PSP release supporting 2.6.37.

    DVFS isn't yet supported on the mainline kernel :(

  • 0 in reply to Sanjeev Premi
    Intellectual 580 points

    Hi Sanjeev,

    As per your suggestion I have picked up linux-2.6.32-psp03.00.01.06 whcih came with DVSDK4 and did the following steps to compile it for Gimstix Overo COM board.

    $ make mrproper
    $ make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- overo_defconfig
    #
    # configuration written to .config
    #
    $ make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi-


    The kernel make encounterd the followin error.


      CHK     include/linux/utsrelease.h
      SYMLINK include/asm -> include/asm-arm
      CALL    scripts/checksyscalls.sh
    <stdin>:1523:2: warning: #warning syscall recvmmsg not implemented
      CHK     include/linux/compile.h
      GEN     .version
      CHK     include/linux/compile.h
      UPD     include/linux/compile.h
      CC      init/version.o
      LD      init/built-in.o
      LD      .tmp_vmlinux1
    arch/arm/mach-omap2/built-in.o: In function `omap2_clk_set_freq':
    usb-ehci.c:(.init.text+0x17a0): undefined reference to `omap3_iva_idle'
    make: *** [.tmp_vmlinux1] Error 1
    thalib@SilenStorm:$

     

    Could you give the link, where can I download the latest PSP directly..

    Regards,

    Mohamed Thalib H

  • 0 in reply to Thalib
    TI__Expert 4590 points

    Thalib,

    Thalib said:

    $ make mrproper
    $ make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- overo_defconfig
    #
    # configuration written to .config
    #
    $ make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi-

    The kernel make encounterd the followin error.

    The PSP releases for OMAP3 family officially support OMAP3EVM platform - as of v03.00.01.06 release. Since then BeagleBoard has been added to the supported platforms.
    Specifically to your build failure, I suspect board support for Overo may be missing some platform specific initialization. You could look for corresponding changes in board-omap3evm.c

    Thalib said:

    Could you give the link, where can I download the latest PSP directly..

    The PSP is not available standalone. It is included in SDKs - AMSDK and DVSDK. However, you can track the internal development on PSP development trees at:
    http://arago-project.org/git/projects/?p=linux-omap3.git;a=summary

    Do note that development effort to move on 2.6.37 is in progress.

  • 0 in reply to Sanjeev Premi
    Intellectual 580 points

    Hi I checkout the kernel source from www.sakoman.com. and build it using the overo_defconfig. while booting the kernel it struck with below message.

    regulator_init_complete: incomplete constraints, leaving VDAC on
    regulator_init_complete: incomplete constraints, leaving VMMC1 on
    drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
    Waiting for root device /dev/mmcblk0p2...

    Could you help me.

     

    Regards,

    Thalib.

  • 0 in reply to Thalib
    TI__Expert 4590 points

    Can you share your bootargs?

    Also, where is your root filesystem - On the MMC card? If yes, share the partition info of the card as well.

  • 0 in reply to Sanjeev Premi
    Intellectual 580 points

    Bootargs:


    Kernel command line: console=ttyS2,115200n8 vram=12M omapfb.mode=dvi:1024x768MR-16@60 omapfb.debug=y omapdss.def_disp=dvi root=/dev/mmcblk0p2 rw rootfstype=ext3 rootwait

    Yes I am using the MMC for rootfs


    I have did partation as per the following link. http://www.gumstix.net/Setup-and-Programming/view/Overo-Setup-and-Programming/Creating-a-bootable-microSD-card/111.html

    partation1 - FAT
    partation2 - ext3

    While googling I came accros the below link which explains simlar scenario. I tried it but still not working..

    Board stuck booting! Waiting for root device /dev/mmcblk0p2...
    https://groups.google.com/forum/#!topic/beagleboard/yiPfwGhnx88

    FYI.. If I use other kernle It works fine. only has proble while working with git source.

  • 0 in reply to Thalib
    TI__Expert 4590 points

    Don' t see anything wrong with your bootargs.

    It appears that the board support (for overo) is not complete on the git you are using :( You may want to check with Steve Sakoman.

    BTW, I couldn't find overo_defconfig at:

    http://www.sakoman.com/cgi-bin/gitweb.cgi?p=linux-omap-2.6.git;a=tree;f=arch/arm/configs;h=6c9e0b15a0085c924711bd0c6a23916e5e66e4f3;hb=5b698d68c1a9ebeae76a0e4ca4dbfdb10357143d

  • 0 in reply to Sanjeev Premi
    Intellectual 580 points

    Yes The master branch didn't contain the overo_defconfig file.

    FYI I am using the branch origin/omap3-2.6.35. In that it didn't work.

    with all the same setup, I just pull the origin/omap3-2.6.34-mmc3 branch. Only changing the uImage build form 2.6.34 branch works fine.

    What could be issue.

  • 0 in reply to Thalib
    TI__Expert 4590 points

    I would still say that board support is incomplete on the branch you are using.

    You will have to compare the board implementation between the two branches to identify what is missing.

    Start with any initialization related to MMC. But since the kernel versions are different, i am afraid things to could lead back to incomplete implementation on the branch you are using.

    If you intend to use the git hosted by Steve Sakoman, I would suggest asking him which branch you should be using.