Google Summer of Code Work Kicks Off

Posted on 24. May, 2010 by Bernie Thompson in UD-160-A

Today is the kickoff of coding work for Google SoC 2010 projects.

We’re very excited about the Google funded project to refine USB multiseat on Linux, with the winning proposal from Lucas Nascimento Ferreira at the Federal University of Parana in Brazil.

In addition to providing mentoring, Plugable is also providing donated hardware for this project. Two Plugable Universal Docking stations with recent enhancements for use as a terminal, were just picked up by Lucas in Brazil today. By next month, we expect to have updated versions of the UGA-125-HUB for terminal use to send down.

For those interested in learning more and potentially following Lucas’ work:

And we’ll post periodic status updates here.

Windows, Mac, Linux, and Information Overload

Posted on 24. May, 2010 by Bernie Thompson in Windows

Our philosophy is to support all three of Windows, Mac, and Linux for all of Plugable’s hardware products, to the greatest degree possible. And when there are limits (as there often are) we try to tell you about them up front.

We do this because we know you use a mix of machines, or may be thinking about switching one way or another. And when you invest in a collection of USB devices, you want them to be useful beyond your current computer. That’s what we expect, too.

All this activity can get a little noisy, though. A little too much information.

That’ll be especially true for some exciting but technically involved work that’s happening over the next few months on Linux with the Google Summer of Code project for USB multiseat, which makes use of some of our Plugable hardware.

So if you’re interested in just one platform or another, here is a way to get just the news that you care about, and get rid of the rest of the noise:

And for those wanting an even more customized view — just append /feed to the tail end of any category view on the site, to get an even more specific feed, if you’re interested.

Linux Support For Higher-Res Monitors on Lower-Res DisplayLink Devices

Posted on 21. May, 2010 by Bernie Thompson in udlfb

On Windows and Mac, if you plug in a monitor with a higher resolution than your adapter supports, the driver will automatically fall back to the best common mode between the two.

Linux hasn’t had that support — it would try to set the highest mode the monitor is capable of, often resulting in a black screen. Especially common for the DL-125 chip, with its mode limits of 1440×900/1280×1024.

That’s a shame because the DL-125 chip is a smart choice in many cases – by limiting itself to those lower modes, it stays more consistently within the limits of the USB 2.0 bus, resulting in more consistent performance.

So coinciding with the launch of Plugable’s DisplayLink DL-125 based products (UGA-125 and UGA-125-HUB), changes have been implemented to bring Linux roughly up to the level of Windows and Mac in this area for DisplayLink devices. This also helps devices like the UD-160-A when running on monitors greater than its limit of 1920×1080.

The kernel framebuffer driver udlfb has been enhanced to read the resolution limit from the firmware descriptors of the device, and adhere to it.

On the X server side, we needed a driver which would limit itself to the resulting reduced mode list. Unfortunately, the existing displaylink X server reads EDID directly, and assumes the adapter can do whatever the monitor can do.

We’ve been wanting to get rid of the need for a displaylink-specific X server, and the standard xf86-video-fbdev driver runs with the best existing mode, rather than trying to set a higher one in EDID. So this was a good trigger for converting over.

So xf86-video-fbdev has been enhanced with X Damage protocol support, ported from Roberto’s displaylink driver. This is still a little in-flux from an interface perspective, but from a functional perspective it’s done and fully performant.

So it’s now possible to run with a modified generic fbdev driver, which talks to udlfb, with full performance and without needing defio (although there’s also some good news in the defio space, which will be posted about later).

You can grab the latest udlfb kernel module with a “git clone http://git.plugable.com/webdav/udlfb”. Compile with “make && sudo make install && sudo depmod -a”

And you can grab the latest modified xf86-video-fbdev with a “git clone http://git.plugable.com/webdav/xf86-video-fbdev”. Compile with “./autogen.sh && make && sudo make install”

You’ll need a very recent xorg-macros version (1.4), which in package “sudo apt-get install xutils-dev”

To use the new X server, you must turn on the new “ReportDamage” option to fbdev. Modify your existing xorg conf like this:

Section "Device"
  Identifier "dl"
  Driver "fbdev"
  Option "ReportDamage" "true"
  Option "fbdev" "/dev/fb0"
EndSection

And you should be all set to go. This new X server should work with the existing udlfb in the staging tree of kernel 2.6.31+ for now, as it’s re-using the same original ioctl. But may require modeset changes that are only in 2.6.34+.

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