From: "Lothar Waßmann" <LW@KARO-electronics.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org,
Lars-Peter Clausen <lars@metafoo.de>,
Yong Zhang <yong.zhang0@gmail.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] genirq: Fix race condition in ONESHOT irq handler
Date: Thu, 9 Feb 2012 09:40:09 +0100 [thread overview]
Message-ID: <20275.34409.978854.416870@ipc1.ka-ro> (raw)
In-Reply-To: <alpine.LFD.2.02.1202081123390.2794@ionos>
Hi,
Thomas Gleixner writes:
> On Wed, 8 Feb 2012, Lothar Waßmann wrote:
> > > > The problem arises also with interrupt controllers that latch a level
> > > > triggered IRQ until it is acknowledged (like the i.MX28 does).
> > > > In this case the IRQ status bit will remain asserted after the
> > > > soft-irq finishes and retrigger the interrupt while the interrupt line
> > > > is already deasserted.
> > >
> > > This does not make sense. We acknowledge interrupts via mask_ack_irq()
> > > right on entry of handle_level_irq(). So either the interrupt
> > >
> > That's right. But at that point the IRQ line is still asserted and
> > since it is a level IRQ this will not actually clear the interrupt
> > status bit. Normally the IRQ status bit would self-clear when the IRQ
> > line is being deasserted (in this case by removing the finger from the
> > touch panel). But the i.MX28 leaves the IRQ status bit set and it
> > takes another write to the IRQ status register to remove the bogus IRQ
> > status.
>
> So the question is whether the imx irq chip implementation should
> write to the status register on unmask for level type irqs to avoid
> spurious interrupts being generated in the first place. This is not
> only an optimization for threaded interrupts, afaict this spurious
> effect should happen with non threaded interrupts as well.
>
> Did my patch work for you ?
>
Sorry, I couldn't test it earlier. Yes, it works.
Lothar Waßmann
--
___________________________________________________________
Ka-Ro electronics GmbH | Pascalstraße 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Geschäftsführer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996
www.karo-electronics.de | info@karo-electronics.de
___________________________________________________________
prev parent reply other threads:[~2012-02-09 8:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-06 8:14 [BUG] genirq: Race condition in ONESHOT IRQ handler disabling IRQ forever =?utf-8?Q?Lothar_Wa=C3=9Fmann?=
2012-02-06 10:42 ` Lars-Peter Clausen
2012-02-07 9:03 ` Yong Zhang
2012-02-07 10:01 ` Lothar Waßmann
2012-02-07 12:34 ` Yong Zhang
2012-02-07 12:52 ` Lothar Waßmann
2012-02-07 13:07 ` Lars-Peter Clausen
2012-02-07 13:38 ` [PATCH] genirq: Fix race condition in ONESHOT irq handler Lothar Waßmann
2012-02-07 17:03 ` Thomas Gleixner
2012-02-08 6:05 ` Lothar Waßmann
2012-02-08 10:38 ` Thomas Gleixner
2012-02-09 8:40 ` Lothar Waßmann [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20275.34409.978854.416870@ipc1.ka-ro \
--to=lw@karo-electronics.de \
--cc=lars@metafoo.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=yong.zhang0@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).