drm/i915: Automatic i915_switch_context for legacy

During request construction, after pinning the context we know whether
or not we have to emit a context switch. So move this common operation
from every caller into i915_gem_request_alloc() itself.

v2: Always submit the request if we emitted some commands during request
construction, as typically it also involves changes in global state.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171120102002.22254-2-chris@chris-wilson.co.uk

10 files changed, 14 insertions, 43 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 61ba321e9970..e07eb0beef13 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5045,7 +5045,7 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915)
                         goto out_ctx;
                 }
 
-                err = i915_switch_context(rq);
+                err = 0;
                 if (engine->init_context)
                         err = engine->init_context(rq);
 
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 2db040695035..c1efbaf02bf2 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -842,8 +842,7 @@ int i915_switch_context(struct drm_i915_gem_request *req)
         struct intel_engine_cs *engine = req->engine;
 
         lockdep_assert_held(&req->i915->drm.struct_mutex);
-        if (i915_modparams.enable_execlists)
-                return 0;
+        GEM_BUG_ON(i915_modparams.enable_execlists);
 
         if (!req->ctx->engine[engine->id].state) {
                 struct i915_gem_context *to = req->ctx;
@@ -899,7 +898,6 @@ int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv)
 
         for_each_engine(engine, dev_priv, id) {
                 struct drm_i915_gem_request *req;
-                int ret;
 
                 if (engine_has_idle_kernel_context(engine))
                         continue;
@@ -922,10 +920,7 @@ int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv)
                                                                  GFP_KERNEL);
                 }
 
-                ret = i915_switch_context(req);
                 i915_add_request(req);
-                if (ret)
-                        return ret;
         }
 
         return 0;
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index b7895788bc75..14d9e61a1e06 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1111,10 +1111,6 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
         if (err)
                 goto err_request;
 
-        err = i915_switch_context(rq);
-        if (err)
-                goto err_request;
-
         err = eb->engine->emit_bb_start(rq,
                                         batch->node.start, PAGE_SIZE,
                                         cache->gen > 5 ? 0 : I915_DISPATCH_SECURE);
@@ -1960,10 +1956,6 @@ static int eb_submit(struct i915_execbuffer *eb)
         if (err)
                 return err;
 
-        err = i915_switch_context(eb->request);
-        if (err)
-                return err;
-
         if (eb->args->flags & I915_EXEC_GEN7_SOL_RESET) {
                 err = i915_reset_gen7_sol_offsets(eb->request);
                 if (err)
diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 91eae1b20c42..86e2346357cf 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -624,6 +624,10 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
         if (ret)
                 goto err_unpin;
 
+        ret = intel_ring_wait_for_space(ring, MIN_SPACE_FOR_ADD_REQUEST);
+        if (ret)
+                goto err_unreserve;
+
         /* Move the oldest request to the slab-cache (if not in use!) */
         req = list_first_entry_or_null(&engine->timeline->requests,
                                        typeof(*req), link);
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 0f48e666098d..fd150099978c 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -1726,10 +1726,9 @@ static int gen8_switch_to_updated_kernel_context(struct drm_i915_private *dev_pr
                                                          GFP_KERNEL);
         }
 
-        ret = i915_switch_context(req);
         i915_add_request(req);
 
-        return ret;
+        return 0;
 }
 
 /*
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 12e734b29463..be98868115bf 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1592,6 +1592,10 @@ static int ring_request_alloc(struct drm_i915_gem_request *request)
         if (ret)
                 return ret;
 
+        ret = i915_switch_context(request);
+        if (ret)
+                return ret;
+
         request->reserved_space -= LEGACY_REQUEST_SIZE;
         return 0;
 }
diff --git a/drivers/gpu/drm/i915/selftests/huge_pages.c b/drivers/gpu/drm/i915/selftests/huge_pages.c
index 159a2cb68765..db7a0a1f2960 100644
--- a/drivers/gpu/drm/i915/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/selftests/huge_pages.c
@@ -989,13 +989,9 @@ static int gpu_write(struct i915_vma *vma,
         i915_vma_unpin(batch);
         i915_vma_close(batch);
 
-        err = i915_switch_context(rq);
-        if (err)
-                goto err_request;
-
-        err = rq->engine->emit_bb_start(rq,
-                                        batch->node.start, batch->node.size,
-                                        flags);
+        err = engine->emit_bb_start(rq,
+                                    batch->node.start, batch->node.size,
+                                    flags);
         if (err)
                 goto err_request;
 
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
index 4ff30b9af1fe..09340b3c1156 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
@@ -158,10 +158,6 @@ static int gpu_fill(struct drm_i915_gem_object *obj,
                 goto err_batch;
         }
 
-        err = i915_switch_context(rq);
-        if (err)
-                goto err_request;
-
         flags = 0;
         if (INTEL_GEN(vm->i915) <= 5)
                 flags |= I915_DISPATCH_SECURE;
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_request.c b/drivers/gpu/drm/i915/selftests/i915_gem_request.c
index d7bf53ff8f84..647bf2bbd799 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_request.c
@@ -459,10 +459,6 @@ empty_request(struct intel_engine_cs *engine,
         if (IS_ERR(request))
                 return request;
 
-        err = i915_switch_context(request);
-        if (err)
-                goto out_request;
-
         err = engine->emit_bb_start(request,
                                     batch->node.start,
                                     batch->node.size,
@@ -671,9 +667,6 @@ static int live_all_engines(void *arg)
                         goto out_request;
                 }
 
-                err = i915_switch_context(request[id]);
-                GEM_BUG_ON(err);
-
                 err = engine->emit_bb_start(request[id],
                                             batch->node.start,
                                             batch->node.size,
@@ -790,9 +783,6 @@ static int live_sequential_engines(void *arg)
                         }
                 }
 
-                err = i915_switch_context(request[id]);
-                GEM_BUG_ON(err);
-
                 err = engine->emit_bb_start(request[id],
                                             batch->node.start,
                                             batch->node.size,
diff --git a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
index 145bdc26553c..1bbb8c46e2d9 100644
--- a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
+++ b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
@@ -114,10 +114,6 @@ static int emit_recurse_batch(struct hang *h,
         if (err)
                 goto unpin_vma;
 
-        err = i915_switch_context(rq);
-        if (err)
-                goto unpin_hws;
-
         i915_vma_move_to_active(vma, rq, 0);
         if (!i915_gem_object_has_active_reference(vma->obj)) {
                 i915_gem_object_get(vma->obj);
@@ -169,7 +165,6 @@ static int emit_recurse_batch(struct hang *h,
 
         err = rq->engine->emit_bb_start(rq, vma->node.start, PAGE_SIZE, flags);
 
-unpin_hws:
         i915_vma_unpin(hws);
 unpin_vma:
         i915_vma_unpin(vma);