From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/3] ARM: make disable_fiq macro optional
Date: Wed, 8 Feb 2012 08:38:42 +0000 [thread overview]
Message-ID: <20120208083842.GE889@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <4F31AB1E.4010800@gmail.com>
On Tue, Feb 07, 2012 at 04:52:14PM -0600, Rob Herring wrote:
> Wouldn't the fiq be masked then? rpc_init_irq masks out the interrupts
> in the same register as disable_fiq macro:
>
> iomd_writeb(0, IOMD_FIQMASK);
The point of the stuff in disable_fiq is to catch cases where the FIQMASK
register hasn't been disabled, and we receive a spurious FIQ. What happens
in that case (without code in disable_fiq) is that we will endlessly spin
entering and re-entering the FIQ code.
No normal interrupts will be received, and no non-FIQ handler instructions
will ever be executed.
Without this, we're 100% reliant on the FIQMASK register being correctly
set.
I would suggest that other platforms which _can_ receive FIQs should
implement the disable_fiq macro for safety against these kinds of silent
lockups. It shouldn't be needed in the same way that printascii()
shouldn't be needed.
next prev parent reply other threads:[~2012-02-08 8:38 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-06 21:03 [PATCH 0/3] entry-macro.S clean-up Rob Herring
2012-02-06 21:03 ` [PATCH 1/3] ARM: make arch_ret_to_user macro optional Rob Herring
2012-02-06 22:21 ` Nicolas Pitre
2012-02-06 21:03 ` [PATCH 2/3] ARM: make disable_fiq " Rob Herring
2012-02-06 22:34 ` Nicolas Pitre
2012-02-07 5:09 ` Rob Herring
2012-02-07 5:24 ` Nicolas Pitre
2012-02-07 22:52 ` Rob Herring
2012-02-08 8:38 ` Russell King - ARM Linux [this message]
2012-02-08 19:58 ` Rob Herring
2012-02-08 20:14 ` Nicolas Pitre
2012-02-08 20:30 ` Russell King - ARM Linux
2012-02-08 20:52 ` Nicolas Pitre
2012-02-06 21:03 ` [PATCH 3/3] ARM: remove empty disable_fiq and arch_ret_to_user macros Rob Herring
2012-02-06 21:34 ` Jamie Iles
2012-02-06 22:40 ` Nicolas Pitre
2012-02-06 23:01 ` Tony Lindgren
2012-02-07 5:10 ` Linus Walleij
2012-02-07 9:35 ` Nicolas Ferre
2012-02-06 22:22 ` [PATCH 0/3] entry-macro.S clean-up Ryan Mallon
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=20120208083842.GE889@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=linux-arm-kernel@lists.infradead.org \
/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).