R200 DRM/KMS

[Steven Newbury]

On Mon, 2015-07-06 at 15:42 -0400, Alex Deucher wrote:
> On Mon, Jul 6, 2015 at 2:40 PM, Steven Newbury <steve at snewbury.org.uk
> > wrote:
> > On Mon, 2015-07-06 at 12:25 -0400, Alex Deucher wrote:
> > > On Mon, Jul 6, 2015 at 9:39 AM, Steven Newbury <
> > > steve at snewbury.org.uk
> > > > wrote:
> > > > Hi,
> > > > I've been trying to get DRM/KMS working with the current 
> > > > graphics
> > > > stack (xf86-video-ati 7.5, xserver-1.17) on a R200 series 
> > > > card.  I
> > > > assumed this should be working since KMS was implemented for 
> > > > it a
> > > > while back, and it has been working with xf86-video-ati-6.x.
> > > > 
> > > > Unfortunately, it doesn't seem to work.
> > > > 
> > > > I've narrowed it down to drmSetInterfaceVersion() failing when
> > > > called
> > > > from the ATI driver (in radeon_kms.c).  This is a bit strange
> > > > since,
> > > > /sys/class/drm/version correctly reports 1.1.0 20060810. 
> > > >  Presuably
> > > > it's getting the correct fd for the DRM master otherwise it 
> > > > should
> > > > bail earlier?
> > > > 
> > > > 
> > > > Googling confirms others have had the same issue, and 
> > > > generally the
> > > > resolution has been to stick with the old driver.
> > > > 
> > > > Should this be working?  Is it known to be broken?
> > > 
> > > It should be working.  Make sure the kernel driver has kms 
> > > enabled,
> > > firmware available, and that the kernel driver is loaded before
> > > starting X.  If the kernel driver is not loaded before X starts 
> > > you
> > > can get a version mis-match error.
> > 
> > Yes, using Gentoos 4.1.1 kernel, driver is definitely loaded, with
> > modeset=1, which is working, all sysfs entries are there.  gdm 
> > manages
> > to fall back to starting up an X session without using DRM swrast
> > -only, not something you want to experience on such a weak CPU!
> > 
> 
> If the kernel driver loads properly and you get a kms console you
> should be good to go.
> 
> > Manually starting X fails with the "[drm] failed to set drm 
> > interface
> > version." error.
> > 
> 
> Maybe the ddx with that old system was build without KMS support?
Everything is freshly compiled.  The error itself is coming from
radeon_kms.c:651 in the ddx.

> 
> Alex
> 
> > It's a very old system, PCI-only(!) Coppermine-128, belonging to a
> > friend.  The system previously was (very slowly) running Ubuntu 10
> > LTS, I think.  It's not my machine so I'm not able to have 
> > continuous
> > access, but R200 DRM/KMS was working.  Apparently, Ubuntu no longer
> > support R200, so no further updates were possible.
> > 
> > My friend can't afford a new machine at the moment; and since I'm a
> > long time Gentoo dev I took it upon myself to build him a optimized
> > desktop with gcc-5, where possible LTO, -Os, -march=pentium3 with 
> > the
> > system L1 and L2 cache size information.  It's quite possible some
> > part of the gfx stack is miscompiled, I tested it pretty throughly
> > under qemu (with qxl) before deployment, but that of course didn't
> > exercise the R200 driver.  FWIW, other than the failing DRI,
> > performance is surprisingly OK, not super fast obviously, but a 
> > *lot*
> > better than under Ubuntu! (start-up time is alot quicker, by an 
> > order
> > of magnitude!)
> > 
> > I'm attempting to downgrade the xserver and drivers (on the live
> > system) to see if that works, you can imagine that takes a little
> > while on a Coppermine-128!  I'll find out tomorrow.  Otherwise, I
> > guess I'm recompiling the stack with gcc-4.9 and no-LTO...
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