linux-kernel - RE: [RFC trollpatch 1/1] genirq: Remove the fits all and nothing __do

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Date:	Mon, 27 Sep 2010 11:39:29 -0700
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Christoph Hellwig <hch@...radead.org>,
	"linux-alpha@...r.kernel.org" <linux-alpha@...r.kernel.org>,
	"linux-cris-kernel@...s.com" <linux-cris-kernel@...s.com>,
	"linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>,
	Hirokazu Takata <takata@...ux-m32r.org>,
	Greg Ungerer <gerg@...inux.org>, Jeff Dike <jdike@...toit.com>,
	"linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>,
	Chris Zankel <chris@...kel.net>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: RE: [RFC trollpatch 1/1] genirq: Remove the fits all and nothing
 __do_IRQ() code

> No, it's deliberate. The solution is to use the correct flow handler
> for your device. We have currently several flow handlers implemented:

Yes, I found the different "handle_*_irq()" functions. The _percpu_
variant works fine for the ia64 per-cpu interrupt paths.

But *NONE* of them call desc->chip->end() (even though the code flow
in Documentation/DcoBook/genericirq.tmpl says that three of them do
call it].  So it appears that this was thought to be necessary when
the docs were written, but was not put into the code.

The ia64 chip->end function for edge triggered interrupts is a nop(),
so handle_edge_irq() ought to work just fine for it [can't confirm
from my initial tests because the HP box I'm using only has level
triggered ones].

handle_level_irq() works for my level triggered interrupts if I add
a "desc->chip->end(irq)" call to it.

git grep "chip->end" appears to show that the only use of chip->end
is in the "Recovery handler for misrouted interrupts": try_one_irq()

At minimum we seem to have some documentation inconsistencies with
the code.

-Tony

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