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List:       acpi4linux
Subject:    Re: [ACPI] Reboot on shutdown with USB 2.0
From:       Michael Madore <mmadore () aslab ! com>
Date:       2003-03-28 23:41:08
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Grover, Andrew wrote:

>>From: Michael Madore [mailto:mmadore@aslab.com] 
>>    
>>
>
>  
>
>>I'm having a strange problem regarding ACPI and USB 2.0 devices 
>>(External CD-Rom, Jaz drive, etc).  Using 2.4.21-pre5 with the latest 
>>patch if I issue:
>>
>>shutdown -h now
>>
>>The machine shuts off, but half a second later the power 
>>comes back on. 
>> If I unload the echi driver module, the machine shuts off normally.
>>
>>Any thoughts on what would cause that kind of behavior?
>>    
>>
>
>Is this an SMP system? Just curious.
>  
>
Yes, this particular system is SMP.  I'll have to try it with a UP 
kernel just to see if the problem persists.

>What we should be doing (but aren't) is telling each device's driver on
>the system to deactivate its device before we turn off the system power.
>This gives the driver the chance to disable that device's interrupt
>generation. We haven't gotten that far in the driver model work, so what
>we are doing is disabling interrupts and then powering down. This mostly
>works, but isn't really how we want things to work, and is pretty much
>doomed to fail on SMP systems.
>
>I don't know why the ehci device would specifically be the one to cause
>problems...
>  
>
That makes sense, thanks for the explaination.  As a workaround, perhaps 
we can modify the init scripts to unload the ehci driver during shutdown.

Mike Madore



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