GSoC: KMSifying cirrus?

Ian Romanick idr at
Thu Mar 25 11:08:10 PDT 2010

Hash: SHA1

Matt Turner wrote:
> On Wed, Mar 24, 2010 at 4:44 PM, Eric Anholt <eric at> wrote:
>> On Wed, 24 Mar 2010 00:02:20 -0400, Daniel Gnoutcheff <daniel at> wrote:
>>> I'm planing to apply for GSoC, and Xorg is one of the projects I'm
>>> considering. I see that "KMS a non-KMSed driver" is on the ideas list.
>>> One of the ideas I'm considering is the KMSification of the cirrus
>>> driver (at least the alpine half of it). Would there be any interest in
>>> such a project?
>>> Cirrus cards are kind of obsolete, but I suppose *would* be nice to have
>>> one more KMS driver, perhaps a relatively simple one that could be an
>>> easy-to-follow model for other KMSification efforts.
>>> I've got a real CL-GD-5446 to do some testing with, and I've spent a bit
>>> of time tracking/testing/exploring the git repos for the kernel and for
>>> various xorg projects, so I do have a tiny head start there.
>>> More generally, I'm interested in *anything* that will help the free
>>> desktop succeed. :) So I'm choosing projects primarily on the basis of
>>> what I'm best prepared to take on, and where I can be most helpful.
>>> Thanks for any feedback!
>> Sounds like a fun project, and doable.  I'd just recommend that you
>> reduce the scope slightly from a full KMS driver to an unaccelerated KMS
>> driver -- there's going to be a lot of typing and bugfixing before you
>> even get a picture on the screen.  Once you've got an unaccelerated KMS
>> driver, there are a couple of trees out there for X drivers that sit on
>> KMS that you could take advantage of to get a desktop up and running,
>> without having to worry about rearchitecting an existing 2D driver.
>> I think there would be a lot of value beyond just cirrus users in having
>> an unaccelerated KMS example driver -- plenty of (old) hardware out
>> there that could have much nicer linux support using KMS if people saw
>> it was easy to build, since most older accelerators aren't that
>> interesting today.
> This is kind of already my planned GSoC project...
> I'm planning to implement KMS for Permedia3/4 series cards for the
> purpose of providing an example KMS implementation. I'm also planning
> to continue Jesse Barnes' documentation and get it into a usable state
> where someone would be able to pick it up and start coding pretty
> easily.

Matt and I have been talking a bit about this project for the Permedia
chipsets.  I think having two proposals for essentially the same project
on different drivers strengthens both proposals.  Whenever you have two
people trying to do the same thing in different drivers it presents
opportunities to find overlapping functionality (leading to refactoring)
and opportunities to find "best practices."

Since there are a handful of other drivers that ought to get the KMS
treatment, both of these potential side goals seem more valuable than
getting either of those drivers on KMS.  It's one of those teach a man
to fish vs. give a man a fish situations.
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