Change DRAM freq

#1

Hi all,
Can you help me in some unstandard procedure ?
I need to change DRAM freq by some research reasons.
I’ve already made this but on another dev-board.

I coula able by changing multiplicator in the u-boot function kind of
ddr_set_t __ddr_setting[] __attribute__ ((section(".ddr_param"))) =

This DRAM multiplicator describes like:

DRAMFreq: 
 *            {pstate0, pstate1, pstate2, pstate3} //more than one pstate means use dynamic freq

The question is - Can I able to do the same on ROCK 5b dev-board ?
Can somebody help me in that ?

#2

rock5b uses blob TPL from rockchip,

you can technically edit the clock frequency using ddr_bin tool, but i have never tried this myself.

2 Likes
#3

Thanks a lot.
I haven’t heard about this way before.
I’ve used for another dev a such way

Edit file board/khadas/kvim4/firmware/timing.c to find DRAMFreq to change the frequency.

 * DRAMFreq:
 *            {pstate0, pstate1, pstate2, pstate3} //more than one pstate means use dynamic freq
...
                .DramType = CONFIG_DDR_TYPE_LPDDR4,
                .enable_lpddr4x_mode = ENABLE_LPDDR4X_MODE,
                .DRAMFreq ={ 2016,                     0,       0,       0       },
...

Will try. Thanks one more time. For the first glance it looks suitable.

#4

Just to return knowledge to collective intelligence.

Ohhhh. It looks that everything have become much easier then I’ve thought
Just read this.

/sys/class/devfreq/dmc/userspace/set_freq

It provide an ability to set your own freq.
I’ve checked it by stream. Yep. It really works.

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#5

Some benchmark numbers generated with different DMC settings: https://github.com/ThomasKaiser/sbc-bench/issues/55#issuecomment-1309375720

Please note that the DMC ability usually is only there as long as you rely on Rockchip’s outdated BSP kernel (and that’s true for all RK SoCs since a decade). Once you switch to mainline kernel the DMC stuff may be gone.

1 Like
#6

Great point. Thank you.