multihead output bug where? kernel? driver? server?

[Alex Deucher]

On Sat, Feb 28, 2015 at 4:57 AM, Felix Miata <mrmazda at earthlink.net> wrote:
> Whether starting X including this:
> xrandr --dpi 144 --output DVI-0 --mode 1920x1080 --above VGA-0 --output VGA-0
> --primary --mode 1920x1440 # ati dual
>
> works or not depends on which Radeon gfxcard used, and how new the software.
>
> The cards' info:
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/hwinfo-gfx-rv380fan.txt X600
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/hwinfo-gfx-rv516.txt X1300
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/hwinfo-gfx-cedarPC-big41.txt
>
> rv380 works as expected regardless at least as far back as openSUSE 13.1 k3.12.
> openSUSE Tumbleweed 3.19.0:
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440xover1080-rv380fan-OK
>
> cedar works as expected as recently as Mageia 4 k3.12 and openSUSE 13.1 k3.12:
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440over1080-os131-cedarOK
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440-over1080-mag4-cedarOK
>
> Failures in the form of black screen on only one output using rv516 and cedar
> in the following:
> Fedora 20 k3.17.7 cedar (black VGA):
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440bad-over1080OK-f20-cedar
> openSUSE 13.2 k3.16.7 cedar (black VGA):
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440bad-over1080OK-os132-cedar
> Fedora 21 cedar (black VGA):
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440bad-over1080OK-cedarF21-k3177
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440bad-over1080OK-cedarF21-k3187
> openSUSE Tumbleweed k3.19.0 rv516 (black DVI):
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440OKxover1080bad-rv516
> openSUSE Tumbleweed k3.19.0 cedar (black VGA):
> http://fm.no-ip.com/Tmp/Linux/Xorg/ATIdual/xorg.0.log-under1440bad-over1080OK-cedar
>
> All of above pertains to same system, with only changes made being:
>
> 1-which OS booted
> 2-which ATI gfxcard installed
>
> With necessary xrandr output descriptors for Intel, results are as expected
> using onboard Intel gfx instead of ATI PCIe cards.
>
> On cedar in Tumbleweed at least, dropping analog output mode from 1920x1440
> to 1600x1200 produces expected output.
>
> Is this a known ATI driver bug? Somebody else's bug? WAD? Hardware flaws?
> User error?

Sounds like a kernel regression.  Possibly related to the PLL
algorithm changes for HDMI audio.  See:
https://bugzilla.kernel.org/show_bug.cgi?id=91861
I'd suggest opening a new bug.


Alex