drm/i915: put context upon switching

In order to be notified of when the context and all of its associated
objects is idle (for if the context maps to a ppgtt) we need a callback
from the retire handler. We can arrange this by using the kref_get/put
of the context for request tracking and by inserting a request to
demarque the switch away from the old context.

[Ben: fixed minor error to patch compile, AND s/last_context/from/]
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 280617e..efa0ede 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -361,13 +361,13 @@ mi_set_context(struct intel_ring_buffer *ring,
 static int do_switch(struct i915_hw_context *to)
 {
        struct intel_ring_buffer *ring = to->ring;
-       struct drm_i915_gem_object *from_obj = ring->last_context_obj;
+       struct i915_hw_context *from = ring->last_context;
        u32 hw_flags = 0;
        int ret;
 
-       BUG_ON(from_obj != NULL && from_obj->pin_count == 0);
+       BUG_ON(from != NULL && from->obj != NULL && from->obj->pin_count == 0);
 
-       if (from_obj == to->obj)
+       if (from == to)
                return 0;
 
        ret = i915_gem_object_pin(to->obj, CONTEXT_ALIGN, false, false);
@@ -390,7 +390,7 @@ static int do_switch(struct i915_hw_context *to)
 
        if (!to->is_initialized || is_default_context(to))
                hw_flags |= MI_RESTORE_INHIBIT;
-       else if (WARN_ON_ONCE(from_obj == to->obj)) /* not yet expected */
+       else if (WARN_ON_ONCE(from == to)) /* not yet expected */
                hw_flags |= MI_FORCE_RESTORE;
 
        ret = mi_set_context(ring, to, hw_flags);
@@ -405,9 +405,9 @@ static int do_switch(struct i915_hw_context *to)
         * is a bit suboptimal because the retiring can occur simply after the
         * MI_SET_CONTEXT instead of when the next seqno has completed.
         */
-       if (from_obj != NULL) {
-               from_obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
-               i915_gem_object_move_to_active(from_obj, ring);
+       if (from != NULL) {
+               from->obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
+               i915_gem_object_move_to_active(from->obj, ring);
                /* As long as MI_SET_CONTEXT is serializing, ie. it flushes the
                 * whole damn pipeline, we don't need to explicitly mark the
                 * object dirty. The only exception is that the context must be
@@ -415,15 +415,26 @@ static int do_switch(struct i915_hw_context *to)
                 * able to defer doing this until we know the object would be
                 * swapped, but there is no way to do that yet.
                 */
-               from_obj->dirty = 1;
-               BUG_ON(from_obj->ring != ring);
-               i915_gem_object_unpin(from_obj);
+               from->obj->dirty = 1;
+               BUG_ON(from->obj->ring != ring);
+
+               ret = i915_add_request(ring, NULL, NULL);
+               if (ret) {
+                       /* Too late, we've already scheduled a context switch.
+                        * Try to undo the change so that the hw state is
+                        * consistent with out tracking. In case of emergency,
+                        * scream.
+                        */
+                       WARN_ON(mi_set_context(ring, from, MI_RESTORE_INHIBIT));
+                       return ret;
+               }
 
-               drm_gem_object_unreference(&from_obj->base);
+               i915_gem_object_unpin(from->obj);
+               i915_gem_context_unreference(from);
        }
 
-       drm_gem_object_reference(&to->obj->base);
-       ring->last_context_obj = to->obj;
+       i915_gem_context_reference(to);
+       ring->last_context = to;
        to->is_initialized = true;
 
        return 0;

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index d66208c..dac1614 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -135,7 +135,7 @@ struct  intel_ring_buffer {
         */
        bool itlb_before_ctx_switch;
        struct i915_hw_context *default_context;
-       struct drm_i915_gem_object *last_context_obj;
+       struct i915_hw_context *last_context;
 
        void *private;
 };