We have been maintaining a version of the Linux 2.6.20 kernel for around 2 years time now.  Since 2.6.20, a number of features have been added to the mainline kernel which are of interest to us.  Some of these new features are:

• Support for the AT91SAM9G20
• System on chip camera support
• Improved WiFi support
• SDIO and SDHC card support
• Power supply class for managing batteries

In addition to support for new features and drivers, there are a number of benefits to using a recent kernel:

• It is easier to get support with issues and bugs.
• Patches posted on mailing lists are easier to apply to recent kernels.
• It is easier to port patches developed against a recent kernel to be considered for mainline acceptance.

Andrew Morton discussed some of the above benefits in his keynote talk at the CELF Embedded Linux Conference in 2008.  The slides from his talk are available at http://www.celinux.org/elc08_presentations/morton-elc-08.ppt. We choose to use 2.6.29 as the base for our new supported Linux kernel (at the time of writing, the latest stable kernel is 2.6.30).  We have now ported most of the support for our Snapper CL15 and Snapper 9260 Single Board Computer Modules (https://bluewatersys.com/quickstart/) into our 2.6.29 kernel, which is available for download at https://bluewatersys.com/public/linux/linux-2.6.29-snapper.tar.gz. During the upgrade from 2.6.20 to 2.6.29, we have taken the opportunity to drop a large amount of our lecagy code and to clean up other code to better conform to the Linux kernel coding standards.  The long term goal is to improve the maintainability of our kenel code and, wherever possible, push support for our platforms to the mainline kernel in order to ease the upgrade process for ourselves in the future.