Sorry for wrong patch. Please forget about his one. Another one will be submitted.

Alex

On 11/06/2015 01:56 PM, yu....@intel.com wrote:
From: Alex Dai <yu....@intel.com>

Can't immediately free LRC context (neither unpin it) even all
its referenced requests are completed, because HW still need a
short period of time to save data to LRC status page. It is safe
to free LRC when HW completes a request from a different LRC.

Move LRC to ring->last_unpin_ctx when its pin count reaches zero.
Increase ctx refcount to make sure it won't be freed immediately.
When HW complete the next request from a different LRC, release
the last yet-to-be-released one. In the case it is pinned again,
simply decrease its refcount.

Signed-off-by: Alex Dai <yu....@intel.com>
---
  drivers/gpu/drm/i915/intel_lrc.c        | 54 ++++++++++++++++++++++++++++-----
  drivers/gpu/drm/i915/intel_ringbuffer.h |  1 +
  2 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 06180dc..da01d72 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1051,6 +1051,14 @@ static int intel_lr_context_pin(struct 
drm_i915_gem_request *rq)
                if (ret)
                        goto reset_pin_count;
        }
+
+       /* If we are holding this LRC from last unpin, unref it here. */
+       if (ring->last_unpin_ctx == rq->ctx) {
+               rq->ctx->engine[ring->id].pin_count--;
+               i915_gem_context_unreference(rq->ctx);
+               ring->last_unpin_ctx = NULL;
+       }
+
        return ret;
reset_pin_count:
@@ -1058,18 +1066,46 @@ reset_pin_count:
        return ret;
  }
+static void
+lrc_unpin_last_ctx(struct intel_engine_cs *ring)
+{
+       struct intel_context *ctx = ring->last_unpin_ctx;
+       struct drm_i915_gem_object *ctx_obj;
+
+       if (!ctx)
+               return;
+
+       i915_gem_object_ggtt_unpin(ctx->engine[ring->id].state);
+       intel_unpin_ringbuffer_obj(ctx->engine[ring->id].ringbuf);
+
+       WARN_ON(--ctx->engine[ring->id].pin_count);
+       i915_gem_context_unreference(ctx);
+
+       ring->last_unpin_ctx = NULL;
+}
+
  void intel_lr_context_unpin(struct drm_i915_gem_request *rq)
  {
        struct intel_engine_cs *ring = rq->ring;
-       struct drm_i915_gem_object *ctx_obj = rq->ctx->engine[ring->id].state;
-       struct intel_ringbuffer *ringbuf = rq->ringbuf;
- if (ctx_obj) {
-               WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
-               if (--rq->ctx->engine[ring->id].pin_count == 0) {
-                       intel_unpin_ringbuffer_obj(ringbuf);
-                       i915_gem_object_ggtt_unpin(ctx_obj);
-               }
+       if (!rq->ctx->engine[ring->id].state)
+               return;
+
+       WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
+
+       /* HW completes request from a different LRC, unpin the last one. */
+       if (ring->last_unpin_ctx != rq->ctx)
+               lrc_unpin_last_ctx(ring);
+
+       if (--rq->ctx->engine[ring->id].pin_count == 0) {
+               /* Last one should be unpined already */
+               WARN_ON(ring->last_unpin_ctx);
+
+               /* Keep the context pinned and ref-counted */
+               rq->ctx->engine[ring->id].pin_count++;
+               i915_gem_context_reference(rq->ctx);
+
+               ring->last_unpin_ctx = rq->ctx;
        }
  }
@@ -1908,6 +1944,8 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *ring)
        }
lrc_destroy_wa_ctx_obj(ring);
+
+       lrc_unpin_last_ctx(ring);
  }
static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *ring)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h 
b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 58b1976..676d27f 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -267,6 +267,7 @@ struct  intel_engine_cs {
        spinlock_t execlist_lock;
        struct list_head execlist_queue;
        struct list_head execlist_retired_req_list;
+       struct intel_context *last_unpin_ctx;
        u8 next_context_status_buffer;
        u32             irq_keep_mask; /* bitmask for interrupts that should 
not be masked */
        int             (*emit_request)(struct drm_i915_gem_request *request);

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