Reboot Command Makes kernel to hang (MPC8560)

[Kumar Gala]

On Jul 31, 2007, at 6:44 AM, Clemens Koller wrote:

> Hi, Ansari!
>
> Ansari schrieb:
>> Hi Kumar,
>> First of all thanks for ur reply .
>> Even i went through the linux source . And i have observe that the  
>> reboot command used to hard reset the core . I have few doubts can  
>> u please clarify me.
>> 1. Is there any way to reset the full chip with out using any  
>> external signal (MPC8560) ? (like any register that can be used  
>> for reseting the processor)
>
> I RTFM:
> It should be the bits RST[1:0] in the Debug Control Register 0  
> (DBCR0).

This only resets the core on the 8560.

> I didn't find details how the external signals are affected:  
> HRESET_REQ# and friends.
> The HRESET_REQ# is usually fed back to the CPU's HRESET#.
> So if the HRESET_REQ# gets asserted by writing to above registers  
> it should really bring
> down the CPU, it's internal as well as it's external components,  
> which are usually
> connected to a replication of that signal.

This is roughly correct.  The only way on 8560 to generate  
HRESET_REQ# is to cause a core watchdog timeout.

> However the existence of cpm2_reset() and a qe_reset() (QuiccEngine?)
> in the code tells me that the above expectations could be wrong.
>
> Would be nice to have that verified by some hardware guys from  
> freescale...

cpm2_reset/qe_reset are more related to SW than any HW reset.

>
>> 2. Even same reboot command works fine for MPC8540 Processor ?.
>
> ...because it doesn't have a cpm ?

That's more luck than anything else.

>> 3. what are the factors that makes ramdisk hangs . When its  
>> uncompressing ?
>
> Well, side effects ?
>
> Regards,
> -- 
> Clemens Koller
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