drm/i915: add workarounds to gen7_render_ring_flush
From Bspec, Vol 2a, Section 1.9.3.4 "PIPE_CONTROL", intro section detailing the various workarounds: "[DevIVB {W/A}, DevHSW {W/A}]: Pipe_control with CS-stall bit set must be issued before a pipe-control command that has the State Cache Invalidate bit set." Note that public Bspec has different numbering, it's Vol2Part1, Section 1.10.4.1 "PIPE_CONTROL" there. There's also a second workaround for the PIPE_CONTROL command itself: "[DevIVB, DevVLV, DevHSW] {WA}: Every 4th PIPE_CONTROL command, not counting the PIPE_CONTROL with only read-cache-invalidate bit(s) set, must have a CS_STALL bit set" For simplicity we simply set the CS_STALL bit on every pipe_control on gen7+ Note that this massively helps on some hsw machines, together with the following patch to unconditionally set the CS_STALL bit on every pipe_control it prevents a gpu hang every few seconds. This is a regression that has been introduced in the pipe_control cleanup: commit 6c6cf5aa Author: Chris Wilson <chris@chris-wilson.co.uk> Date: Fri Jul 20 18:02:28 2012 +0100 drm/i915: Only apply the SNB pipe control w/a to gen6 It looks like the massive snb pipe_control workaround also papered over any issues on ivb and hsw. Signed-off-by:Paulo Zanoni <paulo.r.zanoni@intel.com> [danvet: squashed both workarounds together, pimped commit message with Bsepc citations, regression commit citation and changed the comment in the code a bit to clarify that we unconditionally set CS_STALL to avoid being hurt by trying to be clever.] Signed-off-by:
Daniel Vetter <daniel.vetter@ffwll.ch>
parent
b3111509
Please register or sign in to comment