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drm/i915/execlists: Wrap tail pointer after reset tweaking

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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: a3aabe86a3 ("drm/i915/execlists: Reinitialise context image after GPU hang")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: <stable@vger.kernel.org> # v4.10+
Link: http://patchwork.freedesktop.org/patch/msgid/20170327130009.4678-1-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
(cherry picked from commit 450362d3fe)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170329121315.1290-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2017-03-29 13:13:15 +01:00 committed by Jani Nikula
parent aa62acfd63
commit dd68f2ba07
2 changed files with 10 additions and 2 deletions
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4
drivers/gpu/drm/i915/intel_lrc.c
View File

@ -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)

8
drivers/gpu/drm/i915/intel_ringbuffer.h
View File

@ -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);