sysbios set DSP pll?

Tim Tan

Other Parts Discussed in Thread: SYSBIOS

Hi,

We are using DVRRDK3 and 8148EVM, recently we tried to turn down the DSP clock speed to 600MHz from Linux, but when the DSP firmware is loaded, it still claims to be running at 750MHz. My question is, does sysbios on DSP actually set the clock speed, or is it just displaying a hardcoded value?

Regards,

Tim

over 12 years ago

0 Steven Connell over 12 years ago

TI__Mastermind 45025 points

Tim,

I believe the CPU speed is set in the platform file (used when building your SYS/BIOS application).

Have you tried the following BIOS APIs yet?

BIOS_getCpuFreq(Types_FreqHz *freq);

BIOS_setCpuFreq(Types_FreqHz *freq);

Steve

0 Badri Narayanan over 12 years ago

TI__Guru 59700 points

No sysbios does not set the DSP PLL.However Sysbios needs to know the frequency at which core is running so that all timer ticks are calibrated correctly. DSP PLL is set only in the uboot. If you change the DSP PLL you will have to modify dvr_rdk/mcfw/interfaces/link_api/system_common.h

Change DSP_FREQ define to appropriate value and rebuild rdk firmware.THis will ensure all ticks are correct.

In RDK 3.5 we have made changes so that PLL value is read directly and programmed so you will not have to modify code when you change core frequency.

0 Tim Tan over 12 years ago in reply to Badri Narayanan

Prodigy 200 points

That answered my question. Thank you all.

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sysbios set DSP pll?