[Bug 100871] radeon fails to initialize one DisplayPort monitor

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=100871

Reg <reg at regproctor.com> changed:

           What    |Removed                     |Added
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                 CC|                            |reg at regproctor.com

--- Comment #11 from Reg <reg at regproctor.com> ---
I think I have the same problem but I have a more complicated setup and because
of that I have been able to identify more symptoms which may help.

In any case, here's everything I have been able to determine but first the
hardware setup: My graphics card is "HD 5870 Eyefinity 6" which has 6
DisplayPorts. I have them setup in a grid of 3 across by 2 down. Each display
is at a resolution of 2560x1440 creating a total work area of 7680x2880 in a
Xinerama setup running on the KDE4 desktop.

I currently have 3 kernels in my grub list which are:
  kernel-3.16.7
  kernel-4.7.0
  kernel-4.7.2

Of these 3.16.7 was with opensuse 13.2 and the other two came into being when I
switched over to Tumbleweed, SUSE's rolling distribution.

With the kernel 3.16.7 I had no problem with all DisplayPorts turning on as
they should all the time. When I changed over to Tumbleweed it still worked
fine. However, the other two kernels would only turn on the first two displays.
That happens during boot long before Xorg gets loaded.

In Xorg the behavior is a little strange when it gets DisplayPorts off from the
kernel. Xorg will acknowledge all 6 displays but it is not able to turn on any
that are initially off when the kernel was handling them. E.g.: the last 4
monitors in the case of the 4.x kernels.

The upshot is that when I go to the multidisplay setup part of KDE all 6
displays are showing as active even though only the first two are turned on in
reality. If I disable and re-enable the displays turned off, they don't turn
on. If I use xrandr to turn them on, no dice. That is, if they are off when the
kernel was handling them they are off for good, nothing in Xorg or KDE can
change it that I have found.

There was a bunch of updates for Tumbleweed a few days ago. With this update
the kernel 4.7.2 was added and 3.16.7 started to not always boot with all the
displays on. In fact, it was consistently leaving out display 0 and 5 (first
and last on the graphics card). However, after much playing with the "radeon."
kernel boot parameters I found that setting radeon.agpmode=-1 seemed to make it
consistently on leave only 1 monitor off, monitor 0. No other "radeon." setting
seemed to help.

However, on several boots I could get variations... I must have rebooted 50+
times last night. Occasionally I would get only 4 of the 6 on and even more
occasionally I would get all 6 on like it should be.

Trying all the "radeon." settings seemed to have no effect on the 4.x kernels
and they still only booted with 2 of the 6 displays on... as if someone hard
coded a 2 output limit in the kernel code for testing and forgot to remove the
test code.

I also found two other curious symptoms on the 3.16.7 kernel:

- If I turn the monitor off and back on while booting that the kernel left off
sometimes I can get the kernel to recognise that display and leave it on during
boot. If it gets to the gui before I can turn off/on the monitor then it's too
late. Again, this is very iffy, some times it works and some times it doesn't.

- Since the latest updates, if I let KDE turn off all the monitors, say I walk
away for a while so that power saving kicks in, then all the monitors that were
on will come back on. However if I leave it too long, like over night, then
some displays may not come back on, and, once they are off when they should be
on again, there is no turning them back on without clearing the KDE cache and
rebooting before that cache gets refreshed. This usually means logging out of
my profile, logging in as root user, clearing my profile's KDE/plasma cache,
rebooting, making sure I get a boot that the kernel turns on all the displays
and the logging in to my profile again... not exactly and long term workable
way to be.

I have attached my dmesg with the 3.16.7 kernel working correctly (I just got
very lucky so I preserved the logs). Tomorrow, I can get you the logs of 3.16.7
not coming up correctly and the other two kernels coming up with only 2
displays on out of the 6 there should be.

That's all that I have figured out so far. As you can guess with my setup it's
rather important that I get this fixed or I'll have to revert back to an older
release which I don't want to do for several reasons. The upshot, I am at your
disposal to figure this out, just tell me what you need me to do.

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