static int do_switch(struct i915_hw_context *to)
{
struct intel_ring_buffer *ring = to->ring;
struct i915_hw_context *from = ring->last_context;
u32 hw_flags = 0;
int ret;
BUG_ON(from != NULL && from->obj != NULL && from->obj->pin_count == 0);
if (from == to)
return 0;
ret = i915_gem_object_pin(to->obj, CONTEXT_ALIGN, false, false);
if (ret)
return ret;
/*
* Pin can switch back to the default context if we end up calling into
* evict_everything - as a last ditch gtt defrag effort that also
* switches to the default context. Hence we need to reload from here.
*/
from = ring->last_context;
/*
* Clear this page out of any CPU caches for coherent swap-in/out. Note
* that thanks to write = false in this call and us not setting any gpu
* write domains when putting a context object onto the active list
* (when switching away from it), this won't block.
*
* XXX: We need a real interface to do this instead of trickery.
*/
ret = i915_gem_object_set_to_gtt_domain(to->obj, false);
if (ret) {
i915_gem_object_unpin(to->obj);
return ret;
}
if (!to->obj->has_global_gtt_mapping)
i915_gem_gtt_bind_object(to->obj, to->obj->cache_level);
if (!to->is_initialized || is_default_context(to))
hw_flags |= MI_RESTORE_INHIBIT;
else if (WARN_ON_ONCE(from == to)) /* not yet expected */
hw_flags |= MI_FORCE_RESTORE;
ret = mi_set_context(ring, to, hw_flags);
if (ret) {
i915_gem_object_unpin(to->obj);
return ret;
}
/* The backing object for the context is done after switching to the
* *next* context. Therefore we cannot retire the previous context until
* the next context has already started running. In fact, the below code
* 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 != 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
* correct in case the object gets swapped out. Ideally we'd be
* 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);
ret = i915_add_request(ring, 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;
}
i915_gem_object_unpin(from->obj);
i915_gem_context_unreference(from);
}
i915_gem_context_reference(to);
ring->last_context = to;
to->is_initialized = true;
return 0;
}
static int do_switch(struct i915_hw_context *to)
{
struct intel_ring_buffer *ring = to->ring;
struct i915_hw_context *from = ring->last_context;
u32 hw_flags = 0;
int ret, i;
BUG_ON(from != NULL && from->obj != NULL && from->obj->pin_count == 0);
if (from == to && !to->remap_slice)
return 0;
ret = i915_gem_obj_ggtt_pin(to->obj, CONTEXT_ALIGN, false, false);
if (ret)
return ret;
/*
* Pin can switch back to the default context if we end up calling into
* evict_everything - as a last ditch gtt defrag effort that also
* switches to the default context. Hence we need to reload from here.
*/
from = ring->last_context;
/*
* Clear this page out of any CPU caches for coherent swap-in/out. Note
* that thanks to write = false in this call and us not setting any gpu
* write domains when putting a context object onto the active list
* (when switching away from it), this won't block.
*
* XXX: We need a real interface to do this instead of trickery.
*/
ret = i915_gem_object_set_to_gtt_domain(to->obj, false);
if (ret) {
i915_gem_object_unpin(to->obj);
return ret;
}
if (!to->obj->has_global_gtt_mapping)
i915_gem_gtt_bind_object(to->obj, to->obj->cache_level);
if (!to->is_initialized || is_default_context(to))
hw_flags |= MI_RESTORE_INHIBIT;
ret = mi_set_context(ring, to, hw_flags);
if (ret) {
i915_gem_object_unpin(to->obj);
return ret;
}
for (i = 0; i < MAX_L3_SLICES; i++) {
if (!(to->remap_slice & (1<<i)))
continue;
ret = i915_gem_l3_remap(ring, i);
/* If it failed, try again next round */
if (ret)
DRM_DEBUG_DRIVER("L3 remapping failed\n");
else
to->remap_slice &= ~(1<<i);
}
/* The backing object for the context is done after switching to the
* *next* context. Therefore we cannot retire the previous context until
* the next context has already started running. In fact, the below code
* 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 != NULL) {
from->obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
i915_vma_move_to_active(i915_gem_obj_to_ggtt(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
* correct in case the object gets swapped out. Ideally we'd be
* 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);
/* obj is kept alive until the next request by its active ref */
i915_gem_object_unpin(from->obj);
i915_gem_context_unreference(from);
}
i915_gem_context_reference(to);
ring->last_context = to;
to->is_initialized = true;
return 0;
}
