From dd68f2ba0720e76c3a5bfa3f639c546f926792f5 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 29 Mar 2017 13:13:15 +0100 Subject: [PATCH] drm/i915/execlists: Wrap tail pointer after reset tweaking If the request->wa_tail is 0 (because it landed exactly on the end of the ringbuffer), when we reconstruct request->tail following a reset we fill in an illegal value (-8 or 0x001ffff8). As a result, RING_HEAD is never able to catch up with RING_TAIL and the GPU spins endlessly. If the ring contains a couple of breadcrumbs, even our hangcheck is unable to catch the busy-looping as the ACTHD and seqno continually advance. v2: Move the wrap into a common intel_ring_wrap(). Fixes: a3aabe86a340 ("drm/i915/execlists: Reinitialise context image after GPU hang") Signed-off-by: Chris Wilson Cc: Mika Kuoppala Cc: # v4.10+ Link: http://patchwork.freedesktop.org/patch/msgid/20170327130009.4678-1-chris@chris-wilson.co.uk Reviewed-by: Mika Kuoppala (cherry picked from commit 450362d3fe866b14304f309b5fffba0c33fbfbc3) Signed-off-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/20170329121315.1290-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/intel_lrc.c | 4 +++- drivers/gpu/drm/i915/intel_ringbuffer.h | 8 +++++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 471af3b480ad..91555d4e9129 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1440,7 +1440,9 @@ static void reset_common_ring(struct intel_engine_cs *engine, GEM_BUG_ON(request->ctx != port[0].request->ctx); /* Reset WaIdleLiteRestore:bdw,skl as well */ - request->tail = request->wa_tail - WA_TAIL_DWORDS * sizeof(u32); + request->tail = + intel_ring_wrap(request->ring, + request->wa_tail - WA_TAIL_DWORDS*sizeof(u32)); } static int intel_logical_ring_emit_pdps(struct drm_i915_gem_request *req) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index 13dccb18cd43..8cb2078c5bfc 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -521,11 +521,17 @@ static inline void intel_ring_advance(struct intel_ring *ring) */ } +static inline u32 +intel_ring_wrap(const struct intel_ring *ring, u32 pos) +{ + return pos & (ring->size - 1); +} + static inline u32 intel_ring_offset(struct intel_ring *ring, void *addr) { /* Don't write ring->size (equivalent to 0) as that hangs some GPUs. */ u32 offset = addr - ring->vaddr; - return offset & (ring->size - 1); + return intel_ring_wrap(ring, offset); } int __intel_ring_space(int head, int tail, int size); -- 2.20.1