linux-kernel - Re: [PATCH 6/6 v14] gpio: Add block gpio to several gpio drivers

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

Date:	Thu, 24 Jan 2013 20:17:30 +0800
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Stijn Devriendt <highguy@...il.com>
Cc:	Roland Stigge <stigge@...com.de>, gregkh@...uxfoundation.org,
	grant.likely@...retlab.ca, linus.walleij@...aro.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	w.sang@...gutronix.de, jbe@...gutronix.de, plagnioj@...osoft.com,
	daniel-gl@....net, rmallon@...il.com, sr@...x.de,
	wg@...ndegger.com, mark.rutland@....com, nicolas.ferre@...el.com
Subject: Re: [PATCH 6/6 v14] gpio: Add block gpio to several gpio drivers

On Thu, Jan 24, 2013 at 01:02:38PM +0100, Stijn Devriendt wrote:

> As a fictive example, consider the i2c-bitbang driver, which you could optimize
> by using block-gpio with sda/scl in a single block. By offering the
> block-gpio API
> even when you cannot set all bits at once, you could cause timing issues.
> You might be toggling the clock line before pushing out data, for example.

> The same holds below, for a driver that has separate hi/lo bits.

If there's a strict ordering requirement on updates then I would expect
a user to explictly code that in hardware otherwise there may be
hardware level issues with unpredictable results; besides in general it
seems silly to force users to open code both versions if they don't want
to rely on this API.

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