linux-kernel - Re: [lm-sensors] [PATCH] hwmon: (max6650) Add support for gpiodef

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]

Message-ID: <20131119180007.GB16693@roeck-us.net>
Date:	Tue, 19 Nov 2013 10:00:07 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Laszlo Papp <lpapp@....org>
Cc:	Marcus Folkesson <marcus.folkesson@...il.com>, hjk@...sjkoch.de,
	linux-kernel@...r.kernel.org, lm-sensors@...sensors.org
Subject: Re: [lm-sensors] [PATCH] hwmon: (max6650) Add support for gpiodef

On Tue, Nov 19, 2013 at 08:54:38AM -0800, Guenter Roeck wrote:
> On Tue, Nov 19, 2013 at 04:42:49PM +0000, Laszlo Papp wrote:
> > On Fri, Nov 15, 2013 at 7:52 PM, Marcus Folkesson
> > <marcus.folkesson@...il.com> wrote:
> > >
> > >> This is just one use case of those, you could also use it for
> > >> non-generic gpio functionality, like alarm, "full-on", internal clock,
> > >> external clock, etc. I believe it is always a bit tricky with MFD. I
> > >> personally prefer to put it into the chip driver because this is not
> > >> clearly a generic gpio interface here, and I need to drive it
> > >> dynamically.
> > >
> > > I agree.
> > >
> > > I think the solution with expose the "GPIOs" in sysfs is the right way to
> > > go.
> > > The chip-function is of a dynamic nature and should therefor not be set in
> > > platform data / devicetree.
> > >
> > > As mentioned before, GPIOs should use the gpio subsystem whenever possible,
> > > but the the gpio-functionality is just a subset of
> > > functions these pins may be set to.
> > >
> > > Also, the I think the *real* reason why the entries is called "gpio" is that
> > > it is so the registers are are mentioned in the datasheet.
> > > Everyone that is working with the device will know what it is all about.
> > > I see it more as an register expose than a gpio interface...
> > >
> > > I agree that the entries does not really fit here. But they does not fit
> > > better elsewhere either.
> > > And I don't think they fit worse than the alarm-entries that is already in
> > > mainline.
> > >
> > > Anyway, I think the documentation file should mention what function each
> > > valid value represent.
> > 
> > Yes, makes sense to make the documentation more comprehensive. Thanks.
> > 
> > Any other issues from anyone before submitting a polished version?
> > 
> You'll have to get feedback from Jean. I won't accept the patch.
> 
To add to this: The datasheet clearly states that the pins are GPIO pins,
three of which can be configured as ALERT output, ALL_ON input, or clock
input/output. GPIO pins should be made available to the kernel through
the GPIO subsystem; any clock configuration should be configured through the
clock subsystem if needed. The pin configuration as ALERT output/ALL_ON
input/clock is clearly board specific and should thus be provided as
platform data and/or devicetree data if needed.

The existing GPIO alarm attributes should be removed. The pin values should be
reported as GPIO pin values instead.

Guenter
--
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/