linux-kernel - Re: [PATCH 27/32] gpio: Add support for the FXL6408 GPIO expander.

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]

Message-ID: <878tyexooc.fsf@eliezer.anholt.net>
Date:	Thu, 09 Jun 2016 10:22:27 -0700
From:	Eric Anholt <eric@...olt.net>
To:	Linus Walleij <linus.walleij@...aro.org>,
	Gerd Hoffmann <kraxel@...hat.com>
Cc:	linux-rpi-kernel <linux-rpi-kernel@...ts.infradead.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Ray Jui <rjui@...adcom.com>,
	Scott Branden <sbranden@...adcom.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Alexandre Courbot <gnurou@...il.com>,
	"open list\:BROADCOM BCM281XX\/BCM11XXX\/BCM216XX ARM ARCHITE..." 
	<bcm-kernel-feedback-list@...adcom.com>,
	"open list\:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@...r.kernel.org>,
	"moderated list\:ARM64 PORT \(AARCH64 ARCHITECTURE\)" 
	<linux-arm-kernel@...ts.infradead.org>,
	open list <linux-kernel@...r.kernel.org>,
	"open list\:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 27/32] gpio: Add support for the FXL6408 GPIO expander.

Linus Walleij <linus.walleij@...aro.org> writes:

> On Wed, Jun 1, 2016 at 11:43 PM, Gerd Hoffmann <kraxel@...hat.com> wrote:
>
>> +#define FXL6408_OUTPUT                 0x05
>> +/* Bits here make the output High-Z, instead of the OUTPUT value. */
>> +#define FXL6408_OUTPUT_HIGH_Z          0x07
> (...)
>> +       /* Disable High-Z of outputs, so that our OUTPUT updates
>> +        * actually take effect.
>> +        */
>> +       i2c_smbus_write_byte_data(client, FXL6408_OUTPUT_HIGH_Z, 0);
>
> High-Z is probably the same as open drain right? And if not open drain,
> it is push-pull.
>
> So you want to implement .set_single_ended() for configuring the lines in
> "high-z", i.e. open drain output mode.

I'll keep this in mind for whenever I end up writing my next GPIO
driver, but this one is dead for now (not actually usable because of the
closed firmware).

Download attachment "signature.asc" of type "application/pgp-signature" (819 bytes)