From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: H Hartley Sweeten <hartleys@visionengravers.com>
Cc: "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>
Subject: Re: Question: I2C touchscreen controller
Date: Wed, 24 Aug 2011 13:46:17 -0700 [thread overview]
Message-ID: <20110824204617.GA13677@core.coreip.homeip.net> (raw)
In-Reply-To: <ADE657CA350FB648AAC2C43247A983F001F388575A7F@AUSP01VMBX24.collaborationhost.net>
On Wed, Aug 24, 2011 at 03:19:26PM -0500, H Hartley Sweeten wrote:
> On Wednesday, August 24, 2011 12:55 PM, Dmitry Torokhov wrote:
> > Hi Hartley,
>
> Hello!
>
> > On Wed, Aug 24, 2011 at 01:23:59PM -0500, H Hartley Sweeten wrote:
> >> Hello all,
> >>
> >> I have a question...
> >>
> >> Are there any I2C touchscreen controllers that do not need irq support?
> >>
> >> I have a system with an I2C bus available to connect to the touchscreen
> >> controller but I don't have an IRQ pin available. Right now I'm just
> >> trying to discover if there is a possible solution or if I will need to
> >> modify my board somehow to get an IRQ.
> >
> > Without IRQ you are limited to polling mode which, for touchscreens,
> > needs to be done at fairly high rate to provide adequate responsiveness.
> > This, in turn, will put considerable load on the system thus driving up
> > power requirements... IOW not very suitable for production use, that is
> > why I've been asking people to submit IRQ-driven drivers, if at all
> > possible.
> >
> > If polling is your only option then input-polldev is your friend.
>
> Hmmm... Kind of what I figured.
>
> After looking a bit deeper it appears I do have and IRQ pin available. It's
> just a bit of a pain to get to... ;-)
>
> It looks like these are the current I2C touchscreen drivers in mainline:
>
> CONFIG_TOUCHSCREEN_88PM860X pmic mfd device? probably not standalone
> CONFIG_TOUCHSCREEN_AD7879_I2C datasheet looks simple enough
> CONFIG_TOUCHSCREEN_ATMEL_MXT needs firmware? probably complicated
I do not believe you'll need custom firmware for this one. I think it is
being used in Samsung's Galaxy S series...
> CONFIG_TOUCHSCREEN_BU21013 can't find a datasheet
> CONFIG_TOUCHSCREEN_CY8CTMG110 looks like the chip may be obsolete
> CONFIG_TOUCHSCREEN_MAX11801 Maxim usually has long lead times
> CONFIG_TOUCHSCREEN_MCS5000 can't find a datasheet
> CONFIG_TOUCHSCREEN_STMPE datasheet looks simple enough
> CONFIG_TOUCHSCREEN_TSC2007 datasheet looks simple enough
>
> Based on that I'm considering the Analog Devices, STMicro, and TI parts.
>
> Do you know if any of these work better than the others?
No, I do not, sorry.
--
Dmitry
next prev parent reply other threads:[~2011-08-24 20:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-24 18:23 Question: I2C touchscreen controller H Hartley Sweeten
2011-08-24 19:54 ` Dmitry Torokhov
2011-08-24 20:19 ` H Hartley Sweeten
2011-08-24 20:46 ` Dmitry Torokhov [this message]
2011-08-25 7:23 ` Henrik Rydberg
2011-08-26 17:06 ` H Hartley Sweeten
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