From: Paulo Zanoni Date: Fri, 17 Aug 2012 21:35:43 +0000 (-0300) Subject: drm/i915: add workarounds to gen7_render_ring_flush X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f39876317a69a104eeaed002d4085348e871bfd1;p=linux-beck.git 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 6c6cf5aa9c583478b19e23149feaa92d01fb8c2d Author: Chris Wilson 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 [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 --- diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 42a4b85b0eae..55cdb4d30a16 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -262,6 +262,25 @@ gen6_render_ring_flush(struct intel_ring_buffer *ring, return 0; } +static int +gen7_render_ring_cs_stall_wa(struct intel_ring_buffer *ring) +{ + int ret; + + ret = intel_ring_begin(ring, 4); + if (ret) + return ret; + + intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4)); + intel_ring_emit(ring, PIPE_CONTROL_CS_STALL | + PIPE_CONTROL_STALL_AT_SCOREBOARD); + intel_ring_emit(ring, 0); + intel_ring_emit(ring, 0); + intel_ring_advance(ring); + + return 0; +} + static int gen7_render_ring_flush(struct intel_ring_buffer *ring, u32 invalidate_domains, u32 flush_domains) @@ -271,6 +290,16 @@ gen7_render_ring_flush(struct intel_ring_buffer *ring, u32 scratch_addr = pc->gtt_offset + 128; int ret; + /* + * Ensure that any following seqno writes only happen when the render + * cache is indeed flushed. + * + * Workaround: 4th PIPE_CONTROL command (except the ones with only + * read-cache invalidate bits set) must have the CS_STALL bit set. We + * don't try to be clever and just set it unconditionally. + */ + flags |= PIPE_CONTROL_CS_STALL; + /* Just flush everything. Experiments have shown that reducing the * number of bits based on the write domains has little performance * impact. @@ -278,11 +307,6 @@ gen7_render_ring_flush(struct intel_ring_buffer *ring, if (flush_domains) { flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH; flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH; - /* - * Ensure that any following seqno writes only happen - * when the render cache is indeed flushed. - */ - flags |= PIPE_CONTROL_CS_STALL; } if (invalidate_domains) { flags |= PIPE_CONTROL_TLB_INVALIDATE; @@ -295,6 +319,11 @@ gen7_render_ring_flush(struct intel_ring_buffer *ring, * TLB invalidate requires a post-sync write. */ flags |= PIPE_CONTROL_QW_WRITE; + + /* Workaround: we must issue a pipe_control with CS-stall bit + * set before a pipe_control command that has the state cache + * invalidate bit set. */ + gen7_render_ring_cs_stall_wa(ring); } ret = intel_ring_begin(ring, 4);