A Linux Driver For USB-Based Projectors
Earlier this week an email hit the Phoronix news inbox from Antonio Ospite, who has been working on this new driver support along with a Reto Schneider. While some of these small projectors have a VGA/HDMI interface (in which case no special Linux graphics driver is needed under Linux), a growing number of them are USB-based where only a Microsoft Windows driver is available. (If you're not familiar with these types of mini/handheld projectors, see the Texas Instruments projector demo from X@FOSDEM.)
With originally targeting an Acer C110, which is based upon an Actions Micro AM7212P chipset, a new open-source driver was born. For the USB projectors there's a simple packet-based protocol for the display ASIC to exchange the data between the host and the projector. Besides the Acer C110, this is reportedly the same design as several other Acer C-Series projectors, Philis PicoPix projectors, the CEL-TEC MP-o1, and various off-brand USB projectors.
Writing this new USB projector driver required reverse-engineering the USB protocol by USB dumps and disassembling the Microsoft Windows driver blob. According to the developers, their implementation will work on any lubusb-1.0 host, even if it's Google's Android platform.
This new ACM7xxx series driver though isn't a DRM/KMS driver or an X.Org driver (nor a V4L2/fbdev driver either for that matter) but more in the form of a user-space library with a display daemon that can be called upon for displaying content. For more details on the implementation or how to use this open-source USB projector driver, read these two posts.
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