From: Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public•gmane.org>
To: Alan Cox <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public•gmane.org>
Cc: Nicolas Pitre
<nicolas.pitre-QSEj5FYQhm4dnm+yROfE0A@public•gmane.org>,
Stephen Rothwell <sfr-3FnU+UHB4dNDw9hX6IcOSA@public•gmane.org>,
Pawel Moll <pawel.moll-5wv7dgnIgG8@public•gmane.org>,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public•gmane.org,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public•gmane.org>,
Jeff Garzik <jgarzik-H+wXaHxf7aLQT0dZR+AlfA@public•gmane.org>,
linux-ide-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
Randy Dunlap <rdunlap-/UHa2rfvQTnk1uMJSBkQmQ@public•gmane.org>,
linux-next-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
Anton Vorontsov
<cbouatmailru-Re5JQEeQqe8AvxtiuMwx3w@public•gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public•gmane.org>,
Linus Torvalds
<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public•gmane.org>,
Ingo Molnar <mingo-X9Un+BFzKDI@public•gmane.org>,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public•gmane.org
Subject: Re: [PATCH] ata: Don't use NO_IRQ in pata_of_platform driver
Date: Tue, 6 Dec 2011 11:25:45 +0000 [thread overview]
Message-ID: <20111206112545.GQ14542@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20111206110554.53bddd14-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
On Tue, Dec 06, 2011 at 11:05:54AM +0000, Alan Cox wrote:
> > Even better. Avoid the first 16 IRQ numbers altogether - so that ISA
> > drivers which have these numbers hard-encoded in them will see failures
> > if they're expecting standard ISA IRQ numbering.
>
> The ISA bus space is non-discoverable so that doesn't make any sense.
>
> > But.. let's make one thing clear: Alan Cox and Linus have been going on
> > about how IRQ0 should not be used. Let's be crystal clear: even x86
> > uses IRQ0. It happens to be the PIC timer, and that gets claimed early
> > on during the x86 boot. So please don't tell me that x86 avoids IRQ0.
> > It doesn't. It just happens that x86 never shows IRQ0 to anything but
> > the i8253 PIC driver.
>
> x86 has an internal invisible IRQ 0 on some platforms. It's never exposed
> beyond the arch code.
>
> > So lets see how x86 squeels if we make the i8253 PIC driver reject IRQ0.
> > I bet that there'd be absolute fury at such a suggestion.
>
> Actually it would be about ten minutes work to remap it to some other
> number that isn't used. It never goes via request_irq or via any core or
> driver layer code however.
>
> In the ARM case the same is going to be true. If you have IRQ 0 plumbing
> that only goes internally in the arch/arm code - eg an ARM with IRQ 0
> wired to something totally arch specific and non-driver then it's not
> going to break and like the internals of x86 doesn't matter.
>
> > When x86 sorts this out, there _might_ be some more motivation to take
> > such comments seriously. Until then it's more like a joke.
>
> Pity you feel that way, but if ARM wants to continue to break more and
> more as we clean up NO_IRQ for everything else that's your privilege, but
> don't expect any sympathy.
For the platforms I care about, it probably won't break. For those which
do break, it's a matter of fixing their include/mach/irqs.h and the code
in their irqchips to convert the IRQ number to the correct bitmask for
the register.
However, I have suggested in the past that new platforms _should_ avoid
not just IRQ0 but IRQ0-15 (for a completely different reason to that of
'IRQ0 means no IRQ'.) But such comments just get ignored, so I just
don't see the point in doing anything about this. If people experience
breakage, so be it. I too will have little sympathy but not for the same
reason.
next prev parent reply other threads:[~2011-12-06 11:25 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-11 9:11 linux-next: Tree for Oct 11 Stephen Rothwell
2011-10-11 18:26 ` [PATCH -next] x86: perf_event_intel.c needs export.h Randy Dunlap
2011-10-11 18:49 ` linux-next: Tree for Oct 11 (mmc) Randy Dunlap
2011-10-11 19:31 ` mmc core broken dependency on CONFIG_BLOCK (Was: linux-next: Tree for Oct 11 (mmc)) Andrei Warkentin
2011-10-11 21:59 ` Randy Dunlap
2011-10-11 23:20 ` NamJae Jeon
2011-10-11 23:48 ` Andrei Warkentin
2011-10-12 0:16 ` NamJae Jeon
2011-10-12 0:50 ` Andrei Warkentin
2011-10-12 1:55 ` NamJae Jeon
2011-10-11 19:15 ` [PATCH -next] jbd2: fix build when CONFIG_BUG is not enabled Randy Dunlap
2011-10-27 8:06 ` Ted Ts'o
2011-10-11 19:26 ` linux-next: Tree for Oct 11 (mfd/intel_msic.c) Randy Dunlap
2011-10-11 19:32 ` linux-next: Tree for Oct 11 (gpio regulator) Randy Dunlap
2011-10-11 20:22 ` Heiko Stübner
2011-10-11 20:37 ` linux-next: Tree for Oct 11 (ata/pata_of_platform.c) Randy Dunlap
2011-10-14 17:58 ` Randy Dunlap
2011-11-10 13:57 ` Ingo Molnar
2011-11-10 14:25 ` Alan Cox
2011-11-10 15:18 ` [PATCH] ata: Fix build error in pata_of_platform (NO_IRQ usage) Anton Vorontsov
2011-11-10 15:25 ` [PATCH 1/2] of/irq: Get rid of NO_IRQ usage Anton Vorontsov
2011-12-06 21:22 ` Rob Herring
2011-12-06 21:25 ` Linus Torvalds
2011-12-06 23:16 ` [PATCH v3] " Anton Vorontsov
2011-12-07 3:51 ` Rob Herring
[not found] ` <20111206231626.GA31683-wnGakbxT3iijyJ0x5qLZdcN33GVbZNy3@public.gmane.org>
2011-12-07 9:52 ` Wolfram Sang
2011-11-10 15:26 ` [PATCH 2/2] ata: Don't use NO_IRQ in pata_of_platform driver Anton Vorontsov
2011-11-10 15:38 ` Alan Cox
2011-11-10 16:28 ` [PATCH] " Anton Vorontsov
2011-11-10 20:34 ` Jeff Garzik
2011-12-02 19:19 ` Dave Martin
2011-12-02 22:34 ` Anton Vorontsov
2011-12-02 22:40 ` Anton Vorontsov
2011-12-02 22:46 ` Anton Vorontsov
2011-12-02 22:40 ` Linus Torvalds
2011-12-02 23:18 ` [PATCH v2] of/irq: Get rid of NO_IRQ usage Anton Vorontsov
2011-12-02 23:22 ` [PATCH] ata: Don't use NO_IRQ in pata_of_platform driver Alan Cox
2011-12-03 18:56 ` Geert Uytterhoeven
2011-12-02 19:26 ` Dave Martin
2011-12-02 19:28 ` Linus Torvalds
2011-12-02 23:12 ` Benjamin Herrenschmidt
2011-12-05 16:11 ` Dave Martin
2011-12-05 17:40 ` Nicolas Pitre
2011-12-05 18:02 ` Dave Martin
2011-12-05 18:15 ` Geert Uytterhoeven
2011-12-05 18:18 ` Nicolas Pitre
[not found] ` <alpine.LFD.2.02.1112051310150.2357-QuJgVwGFrdf/9pzu0YdTqQ@public.gmane.org>
2011-12-05 18:45 ` Alan Cox
2011-12-05 19:19 ` James Bottomley
2011-12-06 6:13 ` Jean-Christophe PLAGNIOL-VILLARD
[not found] ` <20111206061321.GH9192-RQcB7r2h9QmfDR2tN2SG5Ni2O/JbrIOy@public.gmane.org>
2011-12-06 11:34 ` Alan Cox
2011-12-05 19:16 ` Rob Herring
2011-12-05 20:21 ` Anton Vorontsov
2011-12-05 20:47 ` Rob Herring
[not found] ` <4EDD2DE1.1050606-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2011-12-05 20:53 ` Alan Cox
2011-12-06 9:30 ` Dave Martin
[not found] ` <20111206093000.GA2274-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2011-12-06 10:34 ` Alan Cox
2011-12-06 10:55 ` Russell King - ARM Linux
2011-12-05 19:26 ` Dave Martin
2011-12-05 19:49 ` Nicolas Pitre
2011-12-06 9:37 ` Dave Martin
[not found] ` <20111206093709.GB2274-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2011-12-06 10:46 ` Russell King - ARM Linux
2011-12-06 11:00 ` Geert Uytterhoeven
2011-12-06 11:03 ` Russell King - ARM Linux
2011-12-06 11:10 ` Alan Cox
2011-12-06 11:05 ` Alan Cox
[not found] ` <20111206110554.53bddd14-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2011-12-06 11:25 ` Russell King - ARM Linux [this message]
2011-12-06 12:11 ` Alan Cox
2011-12-06 11:37 ` Dave Martin
2011-12-06 11:49 ` Russell King - ARM Linux
2011-12-06 13:25 ` Dave Martin
2011-12-06 19:56 ` Rob Herring
2011-12-06 19:20 ` Linus Torvalds
2011-12-06 20:00 ` Russell King - ARM Linux
[not found] ` <CA+55aFwZBr+3_S9kU-+m8zN8iwOvn2miuuAy-zt7sUjW_+abBg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-12-06 20:59 ` Uwe Kleine-König
2011-12-06 19:11 ` Nicolas Pitre
[not found] ` <20111205161157.GA27550-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2011-12-05 17:41 ` Alan Cox
2011-11-10 15:35 ` [PATCH] ata: Fix build error in pata_of_platform (NO_IRQ usage) Alan Cox
2011-11-10 18:18 ` linux-next: Tree for Oct 11 (ata/pata_of_platform.c) Jeff Garzik
[not found] ` <20111011201127.455df266dcbffb1d621f8576-3FnU+UHB4dNDw9hX6IcOSA@public.gmane.org>
2011-10-11 20:45 ` linux-next: Tree for Oct 11 (iio/resolver) Randy Dunlap
[not found] ` <4E94AADA.4080204-/UHa2rfvQTnk1uMJSBkQmQ@public.gmane.org>
2011-10-12 8:58 ` Jonathan Cameron
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