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DM8148 CPU Speed

Ajay Bhargav
Intellectual 385 points

Hi,

I am trying to get my processor run at 1Ghz but I am not successful till now. I am using latest PSP release 4.4.0.1. I tried changing arm_dpll_ck clock rate as mentioned in this wiki page
http://processors.wiki.ti.com/index.php/TI81XX_PSP_PM_Clock_Framework_User_Guide#Change_Clock_Rate

but arm frequency seems to be hardcoded at 600Mhz. I then tried with the CPU frequency scaling option but it does not seems to work either.
http://processors.wiki.ti.com/index.php/TI81XX_PSP_PM_DVFS_User_Guide#Frequency_Scaling

while exploring on e2e forum I came across this thread (http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/139159.aspx) where mentioned that DM8148 are not marked to run on 1Ghz. Can anyone from TI side confirm this again?

Regards,

Ajay Bhargav

  • 0
    TI__Genius 15310 points

    Hi Ajay,

    The selection can be done by modifying the macro ARM_PLL_987/1200 based on the Frequency required defined in arch/arm/include/asm/arch-ti81xx/clocks_ti814x.h

    http://processors.wiki.ti.com/index.php/TI81XX_PSP_U-Boot#Changing_ARM_core_Frequency

    BR,

    Viet

  • 0 in reply to Viet Dinh
    Intellectual 385 points

    The link you've mentioned talk about TI816x only not TI814x. moreover i checked in the file arch/arm/include/asm/arch-ti81xx/clocks_ti816x.h (not 814x) of u-boot PSP release 4.4.0.1 and I did not find any Macro named "ARM_PLL_987" or 1200

    Can you please confirm which PSP release uses these Macros?

  • 0 in reply to Ajay Bhargav
    TI__Genius 15310 points

    Ajay,

    Please also see this link:

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/190244/682514.aspx#682514

    BR,

    Viet

  • 0 in reply to Viet Dinh
    Intellectual 385 points

    Viet,

    Thank you so much, Link really helped. I Think my processor is not suppose to run at 1Ghz. I have the same part number that is mentioned in the post. But is it possiblet o overclock it to run at 900Mhz as mentioned in his post? I understand the risks involved.

    Regards,

    Ajay Bhargav

  • 0 in reply to Viet Dinh
    Expert 1015 points

    Hello Viet Dinh:

     I use:

    echo "Config Cortex A8 720MHZ..."
    #cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
    echo -n "userspace" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
    echo -n 720000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

    and I see:

    root@dm814x-evm:~# cat  /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_f
    requencies
    600000 720000 1000000

    So I cant  set 900Mhz,How do you get it ?

             Thansk.

  • 0 in reply to zhichao tan60372
    TI__Guru**** 170625 points

    Hi Zhichao,

    What type is your DM8148 device? CYE1, CYE2 or else (for example, TMX320DM8148BCYE1)?

    Best regards,
    Pavel

  • 0 in reply to Pavel Botev
    Expert 1015 points

    Hello Pavel :

        My DM8148 is CYE2,So accroding to datasheet Table 7-4. Device Operating Points (OPPs) ,It support 1G (1.35V)

       I only  use the following command  I can get the 1G speed rate.

    echo -n 1000000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

    When run a decoder  application, use top commnd  to see the %CPU is lower than before.so run at 1G is ok.

    But:

    1、When run at 1G,I run a QT application,when  refresh the new picture the screen will dithering and then ok.

         So,wheather the LCD parameter should change  if  I update the CPU rate to 1G?

        My lcd parameter is :(/etc/init.d/load-hd-firmware.sh)

       echo 51200,1024/150/150/20,600/10/15/10,1 > /sys/devices/platform/vpss/display1/timings

      Thanks .

                                                                                            zhichao.

  • 0 in reply to zhichao tan60372
    TI__Guru**** 170625 points

    Zhichao,

    I do not think that increasing the CPU freq from 600MHz to 1GHz should impact the LCD resolution&timing parameters.

    Can you try to increase the CPU with the approach from the below post, does it make any difference?

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/204555/725680.aspx#725680

    BR
    Pavel