2010/7/5 Rafał Miłecki <zajec5@xxxxxxxxx>: > W dniu 4 lipca 2010 22:37 użytkownik Dave Airlie <airlied@xxxxxxxxx> napisał: >> 2010/7/5 Rafał Miłecki <zajec5@xxxxxxxxx>: >>> W dniu 4 lipca 2010 22:24 użytkownik Dave Airlie <airlied@xxxxxxxxx> napisał: >>>> 2010/7/5 Rafał Miłecki <zajec5@xxxxxxxxx>: >>>>> AFAIU EXA is collection of operations (Solid, Copy, UploadToScreen, >>>>> DownloadFromScreen) that touch VRAM. So we can tell hardware to move >>>>> xterm window 100px right (Copy) and fill freed place with blue >>>>> (Solid). Is that right? >>>>> >>>>> So my question is: when implementing EXA (in DDX) needs DRM and when >>>>> it does not? I know in case of R6xx-R7xx we had to get DRM first to >>>>> receive EXA. AFAIK it wasn't the case with R1xx-R5xx. >>>>> >>>>> On the other hand some VIA's driver needs DRM for EXA on Chrome9, >>>>> while openChrome claims to support EXA without DRM[1]. >>>>> >>>>> Could someone explain this to me, please? >>>>> >>>>> [1] http://phoronix.com/forums/showthread.php?p=89776 >>>> >>>> Nothing to do with EXA, its up to the driver underneath. >>> >>> That's why I mentioned "implementation" in subject, not EXA itself :) >>> >>> >>>> If the driver can accel the operations without the drm, it doesn't >>>> need the drm, it the driver requires the drm to accel operations then >>>> it needs the drm >>> >>> Any tip why acceleration operations are available on some hardware >>> only with DRM, and sometimes not? Is this related to the way how we >>> send commands to GPU? AFAIK every command submission implementation >>> needs DRM... but somehow in case of r1xx-r5xx it is not true. >> >> You can program some GPUs via MMIO, its slower and you can't DMA >> to/from main memory at all, it just works in an offscreen memory area. >> >> Its generally pointless maintaining these codepaths since nobody tests >> them, and for chips like r600 I don't think MMIO is sufficient to >> program accel engines. >> >> Not so sure on r500 its sufficient either since some regs can't be >> programmed via MMIO properly, but we have the codepaths since they are >> so similiar to r100. > > Ahh, I didn't think of submitting commands using MMIO. Thanks! Yeah its not so much submitting commands, as setting up the 3D engine by hand, and then poking in vertices by hand afterwards. I think at one stage radeonhd wanted to add another path to use VRAM to store IBs, so you could do basic CP accel without a drm however there was much point to this, since you just ended up with yet another codepath that got tested once in a blue moon, and was broken until someone tested it. More codepaths generally doesn't lead to better/faster code. Dave. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
