On 06/11/2014 08:41 AM, Jesse Barnes wrote: > On Wed, 11 Jun 2014 17:39:29 +0200 > Daniel Vetter <daniel at ffwll.ch> wrote: > >> On Wed, Jun 11, 2014 at 5:13 PM, Jesse Barnes <jbarnes at virtuousgeek.org> >> wrote: >>>> - If you have a machine which uses tiled framebuffers and enables >>>> swizzling in the BIOS your code will a) drop the swizzle setup in >>>> gem_init_hw, breaking resume b) not set the swizzle settings correctly >>>> in swizzle_detect, breaking swap in/out and pwrite/pread. Not sure such >>>> a machine exists, but still. >>> >>> This would affect krh's MBA, which is why I wanted testing here... >>> anyway I'll spin a new one and ask krh to test again. >> >> Hm, I've thought the issue with the MBA is that it used tiled fbs, but >> non-swizzled. And then a mess ensued when we've enabled it. But yeah, >> unfortunately with the new logic we need to retest :( > > Ah yeah I think you're right, either way, need more testing. > > Maybe we should have just gone with the first patch to never enable > swizzling based on Art's assertion that it didn't matter. >
I hate to jump into the middle of a conversation that may or may not be related to a patch I just posted... but... There was a very long internal discussion that the Windows guys had with H/W. For Gen8+ H/W recommends disabling CSX swizzle. Technically, BDW still supports it, but there is a bug _somewhere_ that makes it problematic. In any case it goes away for sure with Gen9+, so disabling on Gen8 doesn't hurt. According to the other discussion, the H/W guys say that enabling actually hurts performance slightly, and the driver should leave the swizzle decisions to the memory controller. Stevo
