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Subject: RE: [PATCH] ipic: change ack operation that register
	isaccessedonly when needed
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Li Yang <LeoLi@freescale.com>
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Date: Tue, 04 Dec 2007 18:39:05 +1100
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On Tue, 2007-12-04 at 15:23 +0800, Li Yang wrote:
> > -----Original Message-----
> > From: Benjamin Herrenschmidt [mailto:benh@kernel.crashing.org] 
> > Sent: Tuesday, December 04, 2007 10:16 AM
> > To: Li Yang
> > Cc: galak@kernel.crashing.org; linuxppc-dev@ozlabs.org
> > Subject: RE: [PATCH] ipic: change ack operation that register 
> > isaccessedonly when needed
> > 
> > 
> > On Tue, 2007-12-04 at 10:06 +0800, Li Yang wrote:
> > > > That should be handled by the higher level flow handler. 
> > The generic 
> > > > edge one calls ack and the level one mask_and_ack.
> > > > Just make them do the right thing, no need to test for 
> > the flow type 
> > > > in the low level function.
> > > 
> > > But actually ack is called by edge and per cpu handlers.  
> > Mask_and_ack 
> > > is also called by edge handler when the same interrupt is 
> > already in 
> > > progress.  So I don't think that ack/mask_and_ack 
> > implicates flow type 
> > > by design.
> > 
> > They do and you can pass different irq_chip with different 
> > mask/ack routines if necessary.
> Hi Ben,
> 
> I mean that mask_ack_irq() routine is used by both generic
> handle_edge_irq() and handle_level_irq().  mask_ack_irq doesn't know if
> the flow type is level or edge.  Do you suggest to use different
> irq_chip for level and edge?

That would be an option. I dislike testing the flow type in the fast
path.

Ben.