On 24.07.2012 20:01, Daniel Mack wrote: > On 23.07.2012 18:51, Dmitry Torokhov wrote: >> On Thu, Jul 19, 2012 at 05:36:12PM +0200, Daniel Mack wrote: > >>> Ok, finally I found some time. In general, the patch works fine. The >>> only detail I had to amend was the irqflags, which were changed from >>> IRQF_TRIGGER_RISING/IRQF_TRIGGER_FALLING to >>> IRQF_TRIGGER_HIGH/IRQF_TRIGGER_LOW, which doesn't work as the PXA can't >>> deal with level-based IRQs. Changing this back to RISING/FALLING makes >>> the driver work again. >> >> Hmm, but that would mean we need to restore reading the data in open() >> to make sure we re-arm IRQ in case somebody touched the screen before it >> was opened by userspace... > > I had another look at this and don't really know what to do here. We > definitely need level interrupts for this device as the interrupt line's > level is the only that tells us when we can stop reading from the > device. So it's not just the start condition that bites us here. > > I copied some people that might help find a solution. > > To summarize the problem: The EETI touchscreen is a device that asserts > a GPIO line when it has events to deliver and waits for I2C commands to > empty its buffers. When there are no more buffered events, it will > de-assert the line. > > This device is connected to a PXA GPIO that is only able to deliver edge > IRQs, and the old implemenation was to wait for an interrupt and then > read data as long as the IRQ's corresponding GPIO was asserted. However, > expecting that an IRQ is mappable to a GPIO is not something we should > do, so the only clean solution is to teach the PXA GPIO controller level > IRQs. > > So it boils down to the question: Is there any easy and generic way to > emulate level irq on chips that don't support that natively? Otherwise, we would need some sort of generic irq_to_gpio() again, and the interrupt line the driver listens to must have support for that sort of mapping. Any opinion on this, anyone? Thanks, Daniel -- 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
