linux-kernel - Re: [PATCH] gpio: add support for ITE IT87xx Super I/O GPIO.

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Date:	Mon, 19 Mar 2012 09:39:50 -0700
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	Linus Walleij <linus.walleij@...aro.org>
CC:	Diego Elio Pettenò <flameeyes@...meeyes.eu>,
	Grant Likely <grant.likely@...retlab.ca>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	Denis Turischev <denis@...pulab.co.il>
Subject: Re: [PATCH] gpio: add support for ITE IT87xx Super I/O GPIO.

On Mon, 2012-03-19 at 10:05 -0400, Linus Walleij wrote:
> On Mon, Mar 19, 2012 at 2:56 PM, Guenter Roeck
> <guenter.roeck@...csson.com> wrote:
> > On Mon, Mar 19, 2012 at 04:26:44AM -0400, Linus Walleij wrote:
> 
> >> OK that is pinmuxing, if that is to be software-controlled the place to do
> >> it is in drivers/pinctrl. (Documentation/pinctrl.txt gives the backrgound.)
> (...)
> >>
> > Personally I would not dare touch those pins. If a pin is configured as UART pin
> > (or whatever), it is quite unlikely that it is exposed as GPIO pin. Worst case,
> > changing the configuration may result in broken hardware. Not sure what is supposed
> > to be gained by enabling the user to do that.
> 
> Define "user", pinctrl does not have userspace interfaces if that's
> what you mean.
> 
> If you mean "kernel programmer", these creatures seem to not respect what
> they should and shouldn't poke at ;-)
> 
> The usecase is typically if the hardware is used in two different systems
> where the ROM/bootcode/etc does not set up muxing correctly, or are setup
> in a sub-optimal way (e.g. working but consuming too much power) and the
> kernel needs to get involved. Unless you have any scenario like that, no
> need to worry about it.
> 
Ok, guess that makes sense.

Thanks,
Guenter


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