From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: "Singaravelan Nallasellan" <singaravelann@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Interrupt Handler Invocation
Date: Thu, 18 Sep 2008 19:26:51 +0100 [thread overview]
Message-ID: <20080918192651.0cf315b9@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <3baf3d760809181057o5810f975w15647878a3033b30@mail.gmail.com>
On Thu, 18 Sep 2008 23:27:30 +0530
"Singaravelan Nallasellan" <singaravelann@gmail.com> wrote:
> Hi,
>
> I am currently assuming that the ISR will be invoked repeatedly till
> the ISR says the IRQ is handled. Is it a valid assumption?
> Can somebody throw some light on whether ISR is invoked repeatedly
> when the ISR returns the IRQ is not handled?
That depends whether the IRQ is cleared
> What is the behaviour for edge or level triggered interrupts?
Hardware dependant.
IRQ_HANDLED isn't used to indicate that the IRQ was processed and some
magic should occur, it is used so that the kernel can detect stuck
interrupts.
Generally speaking if you get an edge triggered IRQ and nobody handles it
then it will be lost and you may get the IRQ line stuck unusable forever.
If you get a level triggered IRQ and nobody handles it you will get
stuck repeatedly calling the IRQ handler until the kernel shuts that IRQ
off entirely to try and keep going.
prev parent reply other threads:[~2008-09-18 18:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-18 17:57 Singaravelan Nallasellan
2008-09-18 18:26 ` Alan Cox [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=20080918192651.0cf315b9@lxorguk.ukuu.org.uk \
--to=alan@lxorguk.ukuu.org.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=singaravelann@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
all inboxes | Powered by JetHome®