Quoting Kenneth Graunke (2018-01-05 06:06:34) > On Thursday, January 4, 2018 4:41:35 PM PST Rodrigo Vivi wrote: > > On Thu, Jan 04, 2018 at 11:39:23PM +0000, Kenneth Graunke wrote: > > > On Thursday, January 4, 2018 1:23:06 PM PST Chris Wilson wrote: > > > > Quoting Kenneth Graunke (2018-01-04 19:38:05) > > > > > Geminilake requires the 3D driver to select whether barriers are > > > > > intended for compute shaders, or tessellation control shaders, by > > > > > whacking a "Barrier Mode" bit in SLICE_COMMON_ECO_CHICKEN1 when > > > > > switching pipelines. Failure to do this properly can result in GPU > > > > > hangs. > > > > > > > > > > Unfortunately, this means it needs to switch mid-batch, so only > > > > > userspace can properly set it. To facilitate this, the kernel needs > > > > > to whitelist the register. > > > > > > > > > > Signed-off-by: Kenneth Graunke <kenneth@xxxxxxxxxxxxx> > > > > > Cc: stable@xxxxxxxxxxxxxxx > > > > > --- > > > > > drivers/gpu/drm/i915/i915_reg.h | 2 ++ > > > > > drivers/gpu/drm/i915/intel_engine_cs.c | 5 +++++ > > > > > 2 files changed, 7 insertions(+) > > > > > > > > > > Hello, > > > > > > > > > > We unfortunately need to whitelist an extra register for GPU hang fix > > > > > on Geminilake. Here's the corresponding Mesa patch: > > > > > > > > Thankfully it appears to be context saved. Has a w/a name been assigned > > > > for this? > > > > -Chris > > > > > > There doesn't appear to be one. The workaround page lists it, but there > > > is no name. The register description has a note saying that you need to > > > set this, but doesn't call it out as a workaround. > > > > It mentions only BXT:ALL, but not mention to GLK. > > > > Should we add to both then? > > Well, that's irritating. On the workarounds page, it does indeed say > "BXT" with no mention of GLK. But the workaround text says to set > "SLICE_COMMON_CHICKEN_ECO1 Barrier Mode [...] (bit 7 of MMIO 0x731C)." > > Looking at the register definition for SLICE_COMMON_ECO_CHICKEN1, bit 7 > is "Barrier Mode" on [GLK] only, with no mention of BXT. It's marked > reserved PBC on [SKL+, not GLK, not KBL]. On KBL it's something else. > > I believe Mark saw hangs in tessellation control shader hangs on > Geminilake only, and never saw this issue on Broxton. So, my guess is > that the workaround really is new on Geminilake, and the BXT tag on the > workarounds page is incorrect. (Mark, does that sound right to you?) Hi, I'm back! This fails a selftest on glk as we can't even write to the register 0x731c, or at least can't read from the register. Did bspec ever get updated to include this register & wa? -Chris
