[Intel-gfx] GMA 500 Support

[Dave Airlie]

On Sun, Sep 27, 2009 at 1:26 PM, David A. Greene <greened at obbligato.org> wrote:
> On Saturday 26 September 2009 17:07:39 Ben Gamari wrote:
>
>> On Sat, Sep 26, 2009 at 03:39:53PM -0500, David A. Greene wrote:
>> > I am interested in getting the GMA 500 (Pouslbo) chipset working in
>> > Linux. I've done some small investigating into the (unmaintained) Ubuntu
>> > driver. I believe this should get integrated with the intel-gfx effort
>> > and be an officially supported driver.
>>
>> This doesn't seem like this would make too much sense. The driver at least
>> doesn't belong in xv86-video-intel. For one, it seems that something
>> went horribly wrong in the writing of the psb driver. There is horrible
>> code duplication in the driver and no one has been keeping it up-to-date
>> with the recent changes in the stack.
>
> Yes, there is a lot of duplication.  It is in pretty sorry shape.  It also
> uses the TTM interface instead of GEM.  Is TTM even supported
> anymore in modern kernels/X drivers?  This to me is the biggest
> problem.  Is GEM documented somewhere?  A google search
> didn't turn up anything.

A newer version of TTM is used by radeon in the kernel now. There
is a bit of work involved porting to it, but probably a lot less than
a GEM port. There are descriptions of GEM in the headers files,
and there was a gem txt file at one point.

>> Moreover, the GMA500 hardware is a completely different design from the
>> other GMA products.  The core itself was licensed from a third-party IP
>> core company (a derivative of the PowerVR SGX design from Imagination
>> Technologies). It doesn't look like Imagination is going to release
>> documentation or even a reasonable driver unless someone with power
>> (e.g. Intel or Dell) demands it of them.
>
> But I found this message on this very mailing list:
>
> http://lists.freedesktop.org/archives/intel-gfx/2009-May/002427.html
>
> So apparently someone knows something about this chip and thinks
> it shares at least a small something with i915.
>
> Can anyone clarify?

Poulsbo is pretty much an intel 915 modesetting portion with the
SGX 3D. I think it might even have an i915 2D engine, but I'm not 100% sure
on that.

>
> The open source bits of the existing poulsbo driver expose at least some
> register information and other bits.  What's needed for a small bit of
> 2d acceleration?

Port the current code to either new TTM or GEM, port to current modesetting
tree, fixup userspace DDX driver to work.

> Is the PowerVR core for 2d as well?  I'm confused given the above message.

There is a PVR 2D core, not sure if poulsbo uses it, I think it might
just have the
945 one.

> I definitely understand the problems with that core.  The Ubuntu driver
> includes a firmware blob.  I'm entirely new to graphics drivers.  Is that
> firmware likely dependent on TTM or is it independent of memory management?

Its not a firmware blob AFAIK, its a 3D graphics driver blob, very different,
though maybe there is an SGX firmware blob somewhere.

Dave.