[Bug 48310] New: Slow 2D rendering on r300 with xf86-video-ati-6.14.x

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=48310

             Bug #: 48310
           Summary: Slow 2D rendering on r300 with xf86-video-ati-6.14.x
    Classification: Unclassified
           Product: xorg
           Version: 7.4 (2008.09)
          Platform: x86 (IA32)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/Radeon
        AssignedTo: xorg-driver-ati at lists.x.org
        ReportedBy: freedesktop at slated.org
         QAContact: xorg-team at lists.x.org


2D rendering is very slow, especially noticeable with text in terminal windows.
I've been affected by this problem since xf86-video-ati-6.14.0 (currently on
xf86-video-ati-6.14.3 and xorg-server-1.11.2). Manually setting Option
"ColorTiling" "off" solves the problem.

I did a git bisect and traced the cause to this:

kms/pre-6xx: fix pageflipping with tiling
http://cgit.freedesktop.org/xorg/driver/xf86-video-ati/commit/?id=ef9bfb262db7004bef3704e5d914687e50d3fca4

Which apparently also caused bug #33738. However, that was resolved with this:

KMS Color Tiling requires xserver which supports EXA_MIXED_PIXMAPS.
http://cgit.freedesktop.org/xorg/driver/xf86-video-ati/commit/?id=fcf0cca9c0ab0f692b222f619aee8f1cdad3b519

So AFAICT that commit should have made it into 6.14.3, which is what I have,
but for some reason "ColorTiling" is not being set to "off" by default (with no
predefined xorg.conf), when apparently it needs to be, and that's what that
commit claims to do.

I also note a commit after 6.14.3 which enables tiling by default for xserver
1.9.4.901, however 6.14.4 hasn't yet been pushed downstream (Gentoo).

check for xserver 1.9.4.901 to enable tiling by default
http://cgit.freedesktop.org/xorg/driver/xf86-video-ati/commit/?id=bcdb54fe16ebf2e239b84eebf20e8adfe5094bff

So my questions are:

Is ColorTiling supposed to be on or off for r300 on xorg-server 1.11.2 (i.e.
does it work in theory), and if it's supposed to work then why doesn't it in my
case (i.e. do I have a new bug, or is this an ongoing issue with EXA)?

Is xf86-video-ati-6.14.3 supposed to turn off ColorTiling by default, and if so
then why isn't it doing so in my case (was the commit reversed, or do I have
some weirdness happing)?

Just to be clear, I have a working solution (Option "ColorTiling" "off"), but I
have to create an xorg.conf and specify this manually, and IMO this should be
handled automatically by the xserver instead (e.g. LiveCD scenario), or fixed
if it's an EXA bug.

Please ask if you need further info.

Thanks.

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