On Thu, Feb 16, 2012 at 08:48:07AM -0800, Eric Anholt wrote: > On Thu, 16 Feb 2012 13:11:31 +0100, Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > > No longer needed. > > What this code was for: Before gtt mapping, we were doing software > fallbacks in Mesa with pread/write on pages at a time (or worse) of the > framebuffer. It would regularly result in hitting the same page again, > since I was only caching the last page I'd pulled out, instead of > keeping a whole copy of the framebuffer during the fallback. Urgh, that's not really efficient ;-) I think for s/w fallbacks and readbacks we can presume decent damage tracking (like sna does) on the userspace sides. > Since we've been doing gtt mapping for years at this point, I'm happy to > see the code die. > > I'm not sure about the rest of the code. In particular, for the code > that's switching between gtt and cpu mappings to handle a read/write, > I'm concerned about whether the behavior matches for tiled objects. I > haven't reviewed enough to be sure. Behaviour should match old code if you read/write entire pages (we should have decent set of tests for that). If you do non-cacheline-aligned reads/writes on tiled objects, we might hit an issue, but they should be solveable (I've simply been too lazy to write testcases for this). Not cacheline aligned reads/writes on untiled also work, I've created a set of tests to exercise issues there (and tested the tests by omitting some of the clflushes, i.e. all the clfushes now left _are_ required). If old mesa depends on sub-page reads/writes to tiled objects I need to create the respective tests and double-check the code, otherwise I think we're covered. Do you want me to adapt the tests to check correctness for sub-page reads/writes to tiled objects? Thanks, Daniel -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
