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Re: Is _do_IRQ() not needed anymore ?

To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Subject: Re: Is _do_IRQ() not needed anymore ?
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Date: Fri, 01 Dec 2006 18:34:53 +0300
Cc: vagabon.xyz@gmail.com, linux-mips@linux-mips.org
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Hello.

Sergei Shtylyov wrote:

You can use both irq_cpu and i8259 same time. :)

What's wrong with 8259 I wonder? It's happily converted to genirq by other arches...

Indeed.  I missed other arch's i8259.c had changed.  Maybe we should
update i8259.c entirely.

The question is what flow to use: level/edge ones used in x86 code and actually intended for simplistic controllers, not the likes of 8259 OR the "fasteoi" one used in PowerPC code and (as it turned out in my

Sorry for some confusion: in arch/powerpc/ level flow is always used for 8259 code (just because it fits both leve and edge cases)...

earlier discussion in linuxppc-dev) intended for the controllers that are smart enough to mask off the lower-priority IRQs when getting the top level one acknowledged and unmask them upon EOI command...

However, Benjamin Herrenschmidt said that 8259 should have used fasteoi flow instead since it was intended for that exact type of controllers (he claimed to have proposed this flow initially).

---
Atsushi Nemoto

WBR, Sergei

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