R200 DRM/KMS

[Emil Velikov]

Hi Steven,

A couple of more (wild) ideas, below but first...

On 8 July 2015 at 17:48, Steven Newbury <steve at snewbury.org.uk> wrote:
> On Wed, 2015-07-08 at 17:10 +0100, Emil Velikov wrote:
>> On 8 July 2015 at 14:55, Alex Deucher <alexdeucher at gmail.com> wrote:
>> > On Wed, Jul 8, 2015 at 9:53 AM, Steven Newbury <
>> > steve at snewbury.org.uk> wrote:
>> > >
>> > >
>> > > On Wed Jul 8 14:20:28 2015 GMT+0100, Alex Deucher wrote:
>> > > > On Wed, Jul 8, 2015 at 8:58 AM, Steven Newbury <
>> > > > steve at snewbury.org.uk> wrote:
>> > > > >
>> > > > >
>> > > > > On Tue Jul 7 15:12:28 2015 GMT+0100, Alex Deucher wrote:
>> > > > > > On Tue, Jul 7, 2015 at 9:46 AM, Steven Newbury <
>> > > > > > steve at snewbury.org.uk> wrote:
>> > > > > > >
>> > > > > > > I've tried an xserver-1.16, and ddx, libdrm without LTO
>> > > > > > > and with
>> > > > > > > gcc4.9.  Exactly the same thing.  I wondered whether the
>> > > > > > > unused i810
>> > > > > > > could be interfering but triggering a device "remove"
>> > > > > > > before starting
>> > > > > > > X made no difference.
>> > > > > > >
I've completely missed out on this - you have a i810 in there ? Bth,
I'm not sure how well (if any) our userspace works when mixing UMS and
KMS drivers. Toggling off it in the BIOS, blacklisting the kernel
module, checking if it's the boot vga and if X gets it right are nice
things to test/try.

[snip]
> Sitting on a KMS console, "systemctl start gdm", no plymouth
> installed.
Don't know what gdm is up-to these days but a while back it used to
try bringing one X session for the greeter, quickly tear it down and
bring another one for the desktop. Not a gdm person so don't quote me
on that :-)
Yet if that is (roughly) still the case, a likely race condition is on.

>  It's just during Xserver initialisation that
> drmSetInterfaceVersion() fails.  AFAIK Xserver startup is entirely
> single process, single thread.  I've written a little test utility
> which works fine on the system in question.
>
> Compile attached file with:
> gcc -O2 -o test-drm test-drm.c $(pkg-config --cflags libdrm) $(pkg
> -config --libs libdrm)
>
Your test utility seems to do a lot more than the few lines in
radeon_kms.c. Would it be possible that you're misinterpreted the
output (relative to the Xorg.log) ? I know I would :-)

>
>> Personally I would add a healthy amount of printk/printf though the
>> kernel drm + radeon and the ddx.
>
> I guess it doesn't really matter since patching out the code "fixes"
> it...
As you wish. Personally I tend to give it a bit more before giving up.

As this is getting a bit long/messy I'd suspect that a bugzilla entry
with information/logs might be good. It's up-to you, as I won't be
able to help much more.

Good luck,
Emil