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How can the DSP clock speed be adjusted?

CoolAJ86

Intellectual 680 points

How can the DSP clock speed be adjusted?

And can it be adjusted only at boot, or also at runtime?

other search terms: clock, frequency, speed, rate

over 15 years ago

0 kshin over 15 years ago

TI__Genius 16690 points

Hello,

It can be adjusted at runtime. The detail of the procedure is described in the section 4.12.6.1.4 Processor Clock Control of TRM (SPRUF98H–April 2010–Revised August 2010). DSP is a part of IVA 2.2 subsystem and the clock for IVA 2.2 is derived from DPLL2.

0 CoolAJ86 over 15 years ago in reply to kshin

Intellectual 680 points

So is there a simple way to do that?

via u-boot or kernel options, for example?

For reference: Page 414 - Processor Clock Control

0 kshin over 15 years ago in reply to CoolAJ86

TI__Genius 16690 points

If you are using Linux, these are good resources on that topic.

http://elinux.org/OMAP_Power_Management#DVFS:_Dynamic_Voltage_and_Frequency_Scaling

http://processors.wiki.ti.com/index.php/UserGuidePowerMgmt_PSP_03.00.00.05

0 Punya Prakash over 15 years ago in reply to kshin

TI__Intellectual 1665 points

You could use the bootarg, for example to set it to 125000 mpurate=125, alternatively you can use sysfs interface to change the frequency.

echo "125000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

Regards, Punya

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0 CoolAJ86 over 15 years ago in reply to Punya Prakash

Intellectual 680 points

I want to adjust the speed of the DSP, not just the ARM.

0 CoolAJ86 over 15 years ago in reply to kshin

Intellectual 680 points

I'm confused. Neither of those make any mention of the DSP.

0 kshin over 15 years ago in reply to CoolAJ86

TI__Genius 16690 points

When kernel sets the A8 frequency, it scales the IVA2 frequency to corresponding OPP. Please refer Table 4-15 and Table 4-16. in OMAP35x data manual (SPRS507F) for the OPP definitions.