[Bug 43191] Radeons needs 2D (MACRO) color tiling for optimal performance

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Wed Dec 7 06:49:01 PST 2011


--- Comment #25 from Simon Farnsworth <simon.farnsworth at onelan.co.uk> 2011-12-07 06:49:01 PST ---
Alex Deucher has given me data on Evergreen tiling, which has allowed me to get
to the bottom of this:

Evergreen doesn't have one fixed 2D tiling pattern; it has configurable
per-surface 2D tiling. There are restrictions on which tiling options work
together; the DDX and the kernel currently ignore those.

Doing the math, the worst case alignment required for 2D tiling is 2 megabyte
alignment on my hardware. The settings used for the scanout buffer are marked
in Alex's information as illegal - this will be why I need excessive alignment
to make it appear to function.

It looks like fixing this is going to require changes across the stack - rather
than simply attaching patches to this bug, I will send them to appropriate
mailing lists. (xorg-driver-ati for DDX patches, dri-devel for the kernel,
mesa-dev for Mesa).

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