A KMS Driver Arrives For AST Hardware
Written by Michael Larabel in Linux Kernel on 23 April 2012 at 10:02 AM EDT. 6 Comments
A kernel mode-setting (KMS) driver for new hardware has been published.

Red Hat's David Airlie has published an initial KMS driver for AST, the ASpeed Technologies chips found in some servers with graphics capabilities. This driver supports the AST 2000, 2100, 2200, 2150 and 2300 chipsets.

For those not familiar with ASpeed, an eight-year-old company, their AST2300 is described as an "Advanced PCIe Graphics & Remote Management Processor" with 2D video graphics, native PCI Express support, iKVM, DDR2/DDR3 support, and an ARMv9 400MHz processor. The company has made drivers for Red Hat Enterprise Linux 3/4/5/6, SuSE Linux Enterprise Server 9/10/11, Solaris x86, and various flavors of Windows.

With this being a server-oriented graphics chip, the AST KMS driver design is a bit different from the other Linux KMS drivers and it ends up putting the KMS console into system RAM since the video RAM on these chips tend to be low capacity. The driver then does dirty updates to a copy in the video RAM. When user-space sets a new scanout buffer it then forcefully evicts the video RAM console so X can create a frame-buffer using all of the video RAM.

The AST DRM/KMS driver is using TTM for video memory management.

There isn't going to be a user-space driver for the ASpeed hardware but rather this driver is intended to go with the xf86-video-modesetting DDX driver.

This new ASpeed KMS driver by David Airlie measures in at just over 3,200 lines of code. David Airlie worked on this driver as part of his development efforts for Red Hat so presumably they'll be looking to get this pulled into the mainline tree, likely for the Linux 3.5 kernel.

This initial ASpeed KMS driver can be found for now on dri-devel.

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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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