linux-kernel - Re: PCF857x and 16-bit GPIO expanders

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Date:	Thu, 19 Sep 2013 08:10:59 -0500
From:	Felipe Balbi <balbi@...com>
To:	George Cherian <george.cherian@...com>
CC:	<balbi@...com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>
Subject: Re: PCF857x and 16-bit GPIO expanders

Hi,

On Thu, Sep 19, 2013 at 06:38:13PM +0530, George Cherian wrote:
> On 9/19/2013 6:14 PM, Felipe Balbi wrote:
> >Hi,
> >
> >On Thu, Sep 19, 2013 at 01:43:41PM +0530, George Cherian wrote:
> >>On 9/18/2013 11:06 PM, Felipe Balbi wrote:
> >>>Hi,
> >>>
> >>>On Wed, Sep 18, 2013 at 07:18:04PM +0200, Laurent Pinchart wrote:
> >>>>On Wednesday 18 September 2013 13:16:27 Linus Walleij wrote:
> >>>>>On Tue, Sep 17, 2013 at 9:07 PM, Felipe Balbi <balbi@...com> wrote:
> >>>>>>has anyone ever successfully using gpio-pcf857x.c driver with 16-bit
> >>>>>>gpio expanders ? We're having some issues here where toggling the last
> >>>>>>gpio pin (gpio 15) on a PCF8575 device causes platform to hang and I
> >>>>>>can't come up with any explanation of why would it hang...
> >>>>>Bouncing the question to George, Laurent and Kuninori...
> >>>>I've got a board with a PCF8575 chip, but it uses I/Os 8 to 14 only as far as
> >>>>I know.
> >>>>
> >>>>I can try toggling I/O 15, but that will need to wait until next week as I'm
> >>>>currently travelling without access to the hardware.
> >>>alright, that'd help me a lot :-) Just want to make sure if we're having
> >>>a board issue, or PCF8575 is a bit screwy ;-)
> >>Is it on dra7x-evm if so which pcf device (i2c address)?
> >0x21 IIRC, it's pin 15 on that goes to a discrete mux. I want to toggle
> >the mux ;-)
> >
> I am able to toggle the same via sysfs(pcf8575 @ 0x21gpio15(p17)) and
> it does not hang the board.
> I am using Rev D1 board.
> 
> Log :-
> # cat /sys/kernel/debug/gpio
> .
> ...
>  GPIOs 480-495, i2c/0-0021, pcf8575, can sleep:
>  gpio-481 (id_gpio             ) in  hi
>  gpio-482 (id_gpio             ) in  hi
>  gpio-495 (sysfs               ) out hi
> # echo 0 > /sys/class/gpio/gpio495/value
> # cat /sys/kernel/debug/gpio
> .
> ...
> GPIOs 480-495, i2c/0-0021, pcf8575, can sleep:
>  gpio-481 (id_gpio             ) in  hi
>  gpio-482 (id_gpio             ) in  hi
>  gpio-495 (sysfs               ) out lo

weird... I'll debug here and see if I can still reproduce with
v3.12-rc1. Thanks anyway :-)

cheers

-- 
balbi

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