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RE: CPU Frequency change using PLL

To: "Nori, Soma Sekhar" <>
Subject: RE: CPU Frequency change using PLL
From: Bharathi Subramanian <sbharathi@MidasComm.Com>
Date: Wed, 1 Mar 2006 20:11:52 +0530 (IST)
Cc: Linux MIPS <>
In-reply-to: <>
Original-recipient: rfc822;
On Tue, 28 Feb 2006, Nori, Soma Sekhar wrote:

> > During my try, after changing the PLL Freq, the board is stops
> > running. I feel, it is due to change in SDRAM Refresh rate. Is it
> > right ?? Any body tried this, Kindly share exprience with me. Like
> > how to reprogram the peripherals with-out affecting the operation
> > etc..
> Changing the PLL feeding only to the MIPS should not freeze the
> board. You are likely messing with PLL which feeds the peripherals
> as well. 

No. PLL-A (Low Freq) is feeding to peripherals and PLL-B(High Feeq)  
is feeding the MIPS. To save power, I switch from PLL-B to PLL-A
during run-time. After wirte in to PLL-Reg the MIPS Hangs. No reboot.
> Changing the PLL which feeds the SDRAM will also likely cause memory
> corruption. Try putting the SDRAM in self-refresh for the duration
> of PLL stablization and then re-program the SDRAM refresh rate.

I didn't tried this Self-Refresh trick, Let me try ...

Kindly CC to me.

Thanks :)
Bharathi S

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