Hi,friends, the question about the u-boot and device tree?

郭劲 guojin02 at tsinghua.org.cn
Wed Mar 19 12:22:08 EST 2008


My board is MPC8360EMDS, my bootm command is "bootm uImage ramdisk_ppc
mpc836x_mds.dtb", I used the MPC8360E_PB_K26_20071012-LTIB.iso to generate above
uImage, ramdisk_ppc,mpc836x_mds.dtb. 
If I fill the frequency to zero on mpc836x_mds.dts, then the linux-2.6.22 is
crashed, the output of serial is nothing. if I fill the right frequency value same
as the HRCW on mpc836x_mds.dts, the linux is normal. So I think if the frequency
is zero on mpc836x_mds.dts, the u-boot did not pass the right frequency value to

I think maybe that we need to define some on u-boot, then the u-boot can pass the
parameter to linux dtb?

I also has another question, I modified the HRCW to config the cpu as 660/330/400
MHZ during power on, I used the "clocks" command on u-boot to see that the clock
is real 660/330/400 MHZ, then I changed the frequency value on dts to 660/330/400,
after the bootm command, the linux was not carshed after serial configuration, but
the output is random.

Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing disabled
serial8250.0: ttyS0 at MMIO 0xe0004500 (irq = 16) is a 16550A
[output from serial is random]

I have config the frequency both on HRCW and devie tree is the same, why the
frequency for serial on linux is not right?  Why the 528/260/400 is Ok, the
660/330/400 has problem on serial.

Thank you very much.

>From: Scott Wood <scottwood at freescale.com>
>To:  <guojin02 at tsinghua.org.cn>
>Subject: Re: Hi,friends, the question about the u-boot and device tree?
>Date:Tue, 18 Mar 2008 13:28:41 -0500
>On Thu, Mar 13, 2008 at 11:31:11PM +0800, wrote:
>> I make all the frequency(timebase-frequency;bus-frequency;clock-frequency)
>> on device tree file equal to zero, I think those frequency will filled by
>> during bootm, but in fact, the u-boot did not fill any frequency. after bootm,
>> crashed. Why?
>What board?  Are you using a device-tree-aware u-boot and the three-argument
>form of bootm?  What sort of crash?  How do you know it's not filling in the
>> Why so many document point out that the zero value will be filled by u-boot?
>Because it does. :-)
>If it's not doing so on your board, that needs to be fixed.

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