Doing development on udlfb on Linux 2.6.32, crossed paths with these two quirks. The usb_skeleton.c sample driver appears to run afoul of this problem, resulting in a warn_on during bulk transfer completion, if done the way the sample recommends. Because completion routines can be called with irqs disabled, usb_buffer_free on dma-ready buffers can’t be called […]
I was embarrassed to discover that the ever-popular dlfb “green screen” is broken in subtle ways by the new defio support. So for now with this new driver, DL devices may up with what appears to be gibberish. I didn’t notice, because my test config launches X on the DisplayLink device immediately. In the absence […]
[update May 3, 2012: Support for using fb_defio and the standard, generic X fbdev driver is enabled by default, working, and stable with kernel 3.3 (at least). You’ll get lower CPU consumption and latency with DAMAGE notifications, but on many systems (especially higher end), fbdev is great. And because not everything supports DAMAGE, generic fbdev […]
For a USB virtual graphics solution, performance is critical. For the Linux drivers for DisplayLink devices, there are several patches and alternative implementations that are tough to evaluate, compare (and merge) without hard data. It would be great to know what compression ratio we’re getting, how much data is being sent over USB, etc. So, […]
[Update Dec 29, 2011: udlfb was promoted from the staging to the mainline kernel tree in 2.6.38. And in kernel 3.3 pagefault detection and console are enabled by default. See all our udlfb posts for the latest news.] [Update March 14, 2010: udlfb versions have moved to being released with the Linux kernel. Update on […]
There are three codelines of Linux DisplayLink kernel frambuffer drivers currently in use: udlfb (Roberto De Ioris), which is in the Linux kernel staging tree of 2.6.31 and later, and is enabled by default in some recent distros (Ubuntu 9.10). Capable of working with all DisplayLink devices. displaylink-mod (Roberto De Ioris), which adds dynamic mode […]
The video of the talk mentioned in this previous post, is now online (recently moved from the Linux Foundation site, to youtube in 4 parts). Covering: The potential of USB multiseat Some background and earlier work Live demo of USB multiseat with three Plugable devices Walkthrough of the multiseat scripts for Ubuntu 9.04 (available here) […]
The most common use of the Plugable Docking Station today is to enable a Windows/Mac laptop to plug a single USB cable and gain connectivity to an additional monitor, speakers, network cable, and any other 4 USB devices. But the same hardware can be also used on Linux to extend the computer in a different […]
In getting more background from this talk, it was great to review the videos on ndiyo.org and displaylink.org with all the history and background on the concept of low-cost multiseat. Didn’t want too much history in slides, but it will come up verbally, and it’s a rich and interesting history. The one comment the presentation […]
