On Tue, 2007-12-04 at 18:34 +0800, Li Tony wrote:

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From: Michael Ellerman [mailto:michael@ellerman.id.au] 
Sent: 2007年12月4日 13:38
To: Li Tony
Cc: Li Tony; Gala Kumar; linuxppc-dev
Subject: Re: [PATCH] Add IPIC MSI interrupt support

On Mon, 2007-12-03 at 17:07 +0800, Li Li wrote:

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Hi Michael,

I emulate mpic to write this IPIC MSI routines. :)

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diff --git a/arch/powerpc/platforms/83xx/mpc837x_mds.c 

b/arch/powerpc/platforms/83xx/mpc837x_mds.c
index 6048f1b..dbea34b 100644

--- a/arch/powerpc/platforms/83xx/mpc837x_mds.c
+++ b/arch/powerpc/platforms/83xx/mpc837x_mds.c

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+
+#define	ipic_msi_irq_to_hw(virq)	

((unsigned int)irq_map[virq].hwirq)

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What's wrong with virq_to_hw() ?

viqr_to_hw is not __inline__.

Hmm, ok. The three places you use it you also take a spin 
lock, so I'm not sure the function call's really going to 
kill you performance wise.

I am not very sure about spin_lock influence.
But maybe somebody will change the virq_to_hw implementation.
I will take virq_to_hw instead. 

I mean the time to take the function call should be pretty small
compared to taking and releasing a spinlock - but if you have
performance numbers to prove otherwise let me know :)

I see that the virq_to_hw is do inline in 2.6.22.
Why remove it?

It was made non-inline because modules want to use it, and we didn't
want to export the irq_map to modules as well.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person