linux-kernel - Re: [RFC/PATCH 4/4] gpio: smscece: Add support for gpio IO expander feature

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:	Tue, 21 Aug 2012 15:50:09 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Felipe Balbi <balbi@...com>
Cc:	"Poddar, Sourav" <sourav.poddar@...com>,
	devicetree-discuss@...ts.ozlabs.org,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [RFC/PATCH 4/4] gpio: smscece: Add support for gpio IO
 expander feature

On Tue, Aug 21, 2012 at 03:22:18PM +0300, Felipe Balbi wrote:
> On Tue, Aug 21, 2012 at 05:50:28PM +0530, Poddar, Sourav wrote:

> > If I am understanding correctly, if they both uses the same bit we cannot
> > use both for a particular user. ?

> we can, it's just a bit more complex. If a user request both LOW and
> HIGH, then you start with HIGH, once it triggers, before calling the
> nested IRQ handler, you need to change it LOW. When low triggers, before
> calling the nested IRQ handler, you need to change it to HIGH again. And
> so on. I'm just not sure if that's valid on linux IRQ subsystem.

The given example was for keypress - usually a system would use edge
triggered interrupts in combination with reading the GPIO state rather
than level triggered interrupts.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/