Hey Hans, On Thu, 2015-08-06 at 15:19 +0200, Hans de Goede wrote: > Hi All, > > Many accelerometers used in tablets not only offer acceleration > data along 3 axis, but also have a notion of the orientation of > the tablet (right side up, upside down, rotated 90 degrees > left/right), > currently there is no way to export this info via evdev. > > I think we need to add an axis/switch/? to the linux/uapi/input.h > definitions to support this, as it is useful info to have, and the hw > is likely a more reliable source of this info then deducting it from > the accelerometer readings as is done in e.g. : > > https://github.com/hadess/iio-sensor-proxy/blob/master/src/orientatio > n.c#L60 > > 3 questions: > > 1) Do people agree that it is a good idea to export the hardware's > notation of the orientation through evdev ? If the hardware/firmware exports it, definitely. > 2) What sort of evdev events should orientation changes send, events > on a new axis, or switch events, or ... ? > > 3) The accelerometer hardware I've been looking at sofar typically > generates a hw interrupt for orientation changes, where as reading > the actual acceleration axis typically is a contineous process > requiring polling. The current iio-sensor-proxy code (which also > handles evdev accelerometers) leaves the evdev node closed and > only opens it on a change kevent, which means that we need to > generate change kevents on orientation changes. That's how the pegatron accelerometer worked in the WeTab (see the asus ACPI driver). > Another approach > would be to have 2 separate evdev nodes, one for the orientation > function, and on opening that we enable the irq), and one for > reading accel values and on opening this one we start polling. I'd simply export the orientation metadata as a sysfs property, which would be consumed and proxied by iio-sensor-proxy to the desktop. Cheers -- 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
