<html>
<head>
<base href="https://bugs.freedesktop.org/" />
</head>
<body>
<p>
<div>
<b><a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED --- - three monitors on two radeon cards works with some layouts not others"
href="https://bugs.freedesktop.org/show_bug.cgi?id=81476#c20">Comment # 20</a>
on <a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED --- - three monitors on two radeon cards works with some layouts not others"
href="https://bugs.freedesktop.org/show_bug.cgi?id=81476">bug 81476</a>
from <span class="vcard"><a class="email" href="mailto:agd5f@yahoo.com" title="Alex Deucher <agd5f@yahoo.com>"> <span class="fn">Alex Deucher</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=81476#c19">comment #19</a>)
<span class="quote">>
> I'd believe it as a hardware limitation if inverting the first two monitors
> didn't fix it. If I were willing to physically turn my first two monitors
> upside-down, it would work fine with the given hardware. The hardware can
> display across my three monitors at 4800x1200 as long as two of the screens
> are inverted. We just need to make the software put those screens into the
> hardware the other way up!</span >
As I said before, it only works with rotation because it's scanning out of
different buffers when rotation is enabled. When you enable rotation a shadow
buffer is created which is a rotated duplicate of the sub-region of the entire
desktop. So for the rotated case, the display hw is scanning out of a
1600x1200 surface rather than the full 4800x1200 surface. If you wanted to you
could do something similar for the non-rotated case in the xserver, but that
would incur an extra copy for every update of the desktop in the non-rotated
case.
If you want to test further, try and disable acceleration (Option "NoAccel"
"true" in the device section of your xorg.conf) or use the modesetting driver
(xf86-video-modesetting). You won't be able to use rotation since that
requires acceleration do to the rotated blit, but that will take all
non-display hw factors (3D, etc.) out of the equation.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are the assignee for the bug.</li>
</ul>
</body>
</html>