From: David Miller [mailto:davem@davemloft.net]
From: Mike Frysinger <redacted>
Date: Fri, 29 May 2009 06:49:42 -0400

quoted

the hardware has a dedicated internal IRQ line for the Blackfin MAC.
it makes no sense to mark it as shared.  there is nothing it could
possibly be shared with.

Then why bother messing with the flag away at all?  It doesn't fix
anything.

Well - it fixes a bug seen with CONFIG_DEBUG_SHIRQ.
CONFIG_DEBUG_SHIRQ generates spurious fake interrupts and 
checks if the handler can cope with them. 
This is basically a good thing - however only for real shared
interrupts.

Our handler isn't prepared to handle such fake interrupts.
So two options:
1) Set the proper IRQF flags.
2) Fix the ISR to handle spurious interrupts.

This patch chose option 1) 

-Michael