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Subject: Re: [MPC8272ADS]Cannot start my Linux Kernel
From: jeff angielski <jeff@theptrgroup.com>
To: Scott Wood <scottwood@freescale.com>
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Date: Wed, 21 Jan 2009 10:42:10 -0500
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Cc: linuxppc-dev@ozlabs.org, Jean-Michel Hautbois <jhautbois@gmail.com>
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On Tue, 2009-01-20 at 10:31 -0600, Scott Wood wrote:
> On Tue, Jan 20, 2009 at 11:56:58AM +0100, Jean-Michel Hautbois wrote:
> > Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 16256
> > Kernel command line: root=/dev/ram rw
> > PID hash table entries: 256 (order: 8, 1024 bytes)
> > time_init: decrementer frequency = 25.000000 MHz
> > time_init: processor frequency   = 400.000000 MHz
> > clocksource: timebase mult[a000000] shift[22] registered
> > clockevent: decrementer mult[666] sh�
> 
> That looks like something is failing when the real (as opposed to early
> debug) serial driver starts.  Try commenting out the call to cpm_setbrg
> in drivers/serial/cpm_uart/cpm_uart_cpm2.h; if that makes a difference,
> there's something wrong with the brg node in the device tree.

I used the mpc8272ads as the basis for my mpc8265 port to 2.6 and found
that to get the serial ports to clock correctly, I needed to add
"clock-frequency" to the brg node in the DTS file.  

Here is mine:

brg@119f0 {
	compatible = "mpc8265-brg",
             "fsl,cpm2-brg",
             "fsl,cpm-brg";
	reg = <0x119f0 0x10 0x115f0 0x10>;
	clock-frequency = <0>;
};

Of course, you also need to update your ft_blob_update() in u-boot to
fill in the correct value.

The default values in the cpm2 code did not work for my system clock
configuration.


-- 
Jeff Angielski
The PTR Group
www.theptrgroup.com