drm/i915/bdw: Two-stage execlist submit process
Context switch (and execlist submission) should happen only when
other contexts are not active, otherwise pre-emption occurs.
To assure this, we place context switch requests in a queue and those
request are later consumed when the right context switch interrupt is
received (still TODO).
v2: Use a spinlock, do not remove the requests on unqueue (wait for
context switch completion).
Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
v3: Several rebases and code changes. Use unique ID.
v4:
- Move the queue/lock init to the late ring initialization.
- Damien's kmalloc review comments: check return, use sizeof(*req),
do not cast.
v5:
- Do not reuse drm_i915_gem_request. Instead, create our own.
- New namespace.
Signed-off-by: Michel Thierry <michel.thierry@intel.com> (v1)
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com> (v2-v5)
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
[davnet: Checkpatch + wash-up s/BUG_ON/WARN_ON/.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 26bc063..e81f5f6 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -126,7 +126,8 @@
{
uint64_t desc;
uint64_t lrca = i915_gem_obj_ggtt_offset(ctx_obj);
- BUG_ON(lrca & 0xFFFFFFFF00000FFFULL);
+
+ WARN_ON(lrca & 0xFFFFFFFF00000FFFULL);
desc = GEN8_CTX_VALID;
desc |= LEGACY_CONTEXT << GEN8_CTX_MODE_SHIFT;
@@ -202,14 +203,14 @@
ctx_obj0 = to0->engine[ring->id].state;
BUG_ON(!ctx_obj0);
- BUG_ON(!i915_gem_obj_is_pinned(ctx_obj0));
+ WARN_ON(!i915_gem_obj_is_pinned(ctx_obj0));
execlists_ctx_write_tail(ctx_obj0, tail0);
if (to1) {
ctx_obj1 = to1->engine[ring->id].state;
BUG_ON(!ctx_obj1);
- BUG_ON(!i915_gem_obj_is_pinned(ctx_obj1));
+ WARN_ON(!i915_gem_obj_is_pinned(ctx_obj1));
execlists_ctx_write_tail(ctx_obj1, tail1);
}
@@ -219,6 +220,65 @@
return 0;
}
+static void execlists_context_unqueue(struct intel_engine_cs *ring)
+{
+ struct intel_ctx_submit_request *req0 = NULL, *req1 = NULL;
+ struct intel_ctx_submit_request *cursor = NULL, *tmp = NULL;
+
+ if (list_empty(&ring->execlist_queue))
+ return;
+
+ /* Try to read in pairs */
+ list_for_each_entry_safe(cursor, tmp, &ring->execlist_queue,
+ execlist_link) {
+ if (!req0) {
+ req0 = cursor;
+ } else if (req0->ctx == cursor->ctx) {
+ /* Same ctx: ignore first request, as second request
+ * will update tail past first request's workload */
+ list_del(&req0->execlist_link);
+ i915_gem_context_unreference(req0->ctx);
+ kfree(req0);
+ req0 = cursor;
+ } else {
+ req1 = cursor;
+ break;
+ }
+ }
+
+ WARN_ON(execlists_submit_context(ring, req0->ctx, req0->tail,
+ req1 ? req1->ctx : NULL,
+ req1 ? req1->tail : 0));
+}
+
+static int execlists_context_queue(struct intel_engine_cs *ring,
+ struct intel_context *to,
+ u32 tail)
+{
+ struct intel_ctx_submit_request *req = NULL;
+ unsigned long flags;
+ bool was_empty;
+
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
+ if (req == NULL)
+ return -ENOMEM;
+ req->ctx = to;
+ i915_gem_context_reference(req->ctx);
+ req->ring = ring;
+ req->tail = tail;
+
+ spin_lock_irqsave(&ring->execlist_lock, flags);
+
+ was_empty = list_empty(&ring->execlist_queue);
+ list_add_tail(&req->execlist_link, &ring->execlist_queue);
+ if (was_empty)
+ execlists_context_unqueue(ring);
+
+ spin_unlock_irqrestore(&ring->execlist_lock, flags);
+
+ return 0;
+}
+
static int logical_ring_invalidate_all_caches(struct intel_ringbuffer *ringbuf)
{
struct intel_engine_cs *ring = ringbuf->ring;
@@ -405,8 +465,7 @@
if (intel_ring_stopped(ring))
return;
- /* FIXME: too cheeky, we don't even check if the ELSP is ready */
- execlists_submit_context(ring, ctx, ringbuf->tail, NULL, 0);
+ execlists_context_queue(ring, ctx, ringbuf->tail);
}
static int logical_ring_alloc_seqno(struct intel_engine_cs *ring,
@@ -846,6 +905,9 @@
INIT_LIST_HEAD(&ring->request_list);
init_waitqueue_head(&ring->irq_queue);
+ INIT_LIST_HEAD(&ring->execlist_queue);
+ spin_lock_init(&ring->execlist_lock);
+
ret = intel_lr_context_deferred_create(dctx, ring);
if (ret)
return ret;