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 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
