Silicon Motion Has Open-Source Driver, But Fails

For those that don't closely follow the various development lists, at the end of February a Silicon Motion developer came to the DRI list announcing he had "a kernel driver for all our graphics chips" that he was looking to mainline. It sounds nice, but in the end it's a let-down and the most you'll probably get out of it is a few laughs.

While not too popular these days, Silicon Motion is still around and when it comes to GPUs they're still working on graphics processors for embedded devices and servers. The Silicon Motion embedded graphics primarily target handhelds, point-of-sale terminals, medical equipment, and other devices. Silicon Motion graphics are available on x86, XScale, ARM, MIPS, and PowerPC platforms.

Under Linux, an open-source Silicon Motion X.Org driver has long been available and does feature EXA 2D acceleration, RandR 1.2, and other features, but there isn't much other activity going on within the Silicon Motion world at the moment. There is no Gallium3D driver, no KMS/DRM driver, and the community is quite small. As a result, it was quite interesting when a Silicon Motion developer came to the DRI/DRM mailing list with a "kernel driver" that handled all of their graphics chipsets and wished to mainline it.

In his first message, Aaron Chen, asks how they can submit their driver to kernel.org. The discussion has been ongoing for the past two weeks.

While it seemed hopeful at first, in the end this Silicon Motion Linux work was a let-down. The kernel developer doesn't understand Git and was even attempting to get this Silicon Motion driver integrated into every Linux kernel release from Linux 2.6.5 to Linux 3.0, but that's not the worst part.

When the initial patch work was published, this wasn't even a Silicon Motion DRM/KMS driver. This code was just a Silicon Motion frame-buffer driver for their hardware. Silicon Motion calls this driver "lynxfb" and is said to support the SMI SM712, 722, 718, 750, 750LE, and 502 graphics chips. It looks like it supports a dual-view mode (dual head), hardware cursor handling, all VESA video modes, and 2D acceleration.

The 17,000 line "lynxfb" driver patch from Silicon Motion can be found as this mailing list attachment.

The Silicon Motion LynxFB driver generated around 9,000 coding style errors when tested by a developer.

With that driver that Silicon Motion wants to integrate into the mainline Linux kernel, all of the files are marked "Copyright (c) 2007 by Silicon Motion, Inc. (SMI) All rights are reserved. Reproduction or in part is prohibited without the written consent of the copyright owner." There isn't any GPL references. The files contain old copyrights, so this looks like it's from their once proprietary Linux driver as opposed to a new frame-buffer driver written from scratch.

Perhaps Silicon Motion's proprietary markings were just a mistake? Well, a developer on the list already inquired about it to make sure this driver would be GPL-compatible for the kernel. The response from the Silicon Motion developer, "I don't know about the license thing. Is there any different license for choosing?"

So in the end it's much ruckus over a kernel frame-buffer driver looking to go mainline for niche hardware that might not even be a truly open-source driver.