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- This directory contains the Linux USB Tranzport and Alphatrack Kernel drivers.
- See http://www.frontierdesign.com for details on these devices.
- Userspace test code is available from
- git://toutatis.isc.org/home/d/src/git/frontier.git
- At present the tranzport does reads/writes of 8 byte cmds to
- /dev/tranzport0 to control the lights, screen, and wheel.
- At present the alphatrack accepts reads/writes of 12 byte cmds to
- /dev/tranzport0 to control the lights, screen, fader and touchpad.
- The tranzport driver provides a rudimentary sysfs interface for the status of
- the device and a writable parameter for turning wheel compression on and off.
- The API is nothing more than the USB commands issued to the device. Why?
- The control wheel/fader can generate events far too quickly for
- a typical userspace application to keep up with them via libusb. Input
- needs to be 100% accurate and fast in order for the alphatrack or tranzport
- to be useful.
- UIO would be useful except that usb disconnect events need
- to be handled correctly.
- A sysfs interface is perfect for simple userspace apps to do fun things with
- the lights and screen. But it's fairly lousy for handling input events and
- very lousy for watching the state of the shuttle wheel.
- A linux input events interface is great for the input events and shuttle wheel.
- * It's theoretically OK on LEDs.
- * A fader can be mapped to an absolute mouse device.
- * But there is no LCD support at all, or fader feedback support in that API
- So, thus, these stubby drivers exist.
- In the end this could be driven by a midi layer, which handles all those
- cases via a well defined API, but - among other things - is slow, doesn't do
- flow control, and is a LOT of extra work, none of which is required at
- the kernel level (probably). Frankly, I'd like to keep the
- core driver simple because the only realtime work really required is
- the bottom half interrupt handler and the output overlapping.
- Exposing some sort of clean api to userspace would be perfect. What that
- API looks like? Gah. beats me.
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