linux-kernel - Re: [PATCH RFT] irqchip: sun4i: Remove wrong irq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 24 Jul 2013 11:51:45 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Axel Lin <axel.lin@...ics.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFT] irqchip: sun4i: Remove wrong irq_ack callback
 implementation

Hi Geert,

On Fri, Jul 19, 2013 at 11:29:30AM +0200, Geert Uytterhoeven wrote:
> On Thu, Jul 11, 2013 at 6:13 PM, Maxime Ripard
> <maxime.ripard@...e-electrons.com> wrote:
> > On Sat, Jul 06, 2013 at 10:35:29PM +0800, Axel Lin wrote:
> >> According to the datasheet[1], the Interrupt IRQ Pending Registers are
> >> read-only. The implementation of sun4i_irq_ack() looks wrong because it writes
> >> to these read-only registers.
> >
> > Right, but the datasheet also says that these registers are "clear"
> > register, which might indicate that it's actually R/W.
> 
> I guess it means that the flags are cleared automatically on read?
> That's not so uncommon for interrupt pending registers.

My understanding in this case is that the pending register is just a
"copy" of the pending bits in the related hardware IP, so that clearing
it in the interrupt controller won't do much, since it will be re-set
just after the clear, while if you do clear the interrupt bit in the IP,
it will clear it automatically in the interrupt controller.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Download attachment "signature.asc" of type "application/pgp-signature" (837 bytes)