/**
* The default context needs to exist per ring that uses contexts. It stores the
* context state of the GPU for applications that don't utilize HW contexts, as
* well as an idle case.
*/
static int create_default_context(struct drm_i915_private *dev_priv)
{
struct i915_hw_context *ctx;
int ret;
BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
ctx = create_hw_context(dev_priv->dev, NULL);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
/* We may need to do things with the shrinker which require us to
* immediately switch back to the default context. This can cause a
* problem as pinning the default context also requires GTT space which
* may not be available. To avoid this we always pin the
* default context.
*/
dev_priv->ring[RCS].default_context = ctx;
ret = i915_gem_object_pin(ctx->obj, CONTEXT_ALIGN, false);
if (ret) {
do_destroy(ctx);
return ret;
}
ret = do_switch(NULL, ctx, 0);
if (ret) {
i915_gem_object_unpin(ctx->obj);
do_destroy(ctx);
} else {
DRM_DEBUG_DRIVER("Default HW context loaded\n");
}
return ret;
}
/**
* The default context needs to exist per ring that uses contexts. It stores the
* context state of the GPU for applications that don't utilize HW contexts, as
* well as an idle case.
*/
static int create_default_context(struct drm_i915_private *dev_priv)
{
struct i915_hw_context *ctx;
int ret;
DRM_LOCK_ASSERT(dev_priv->dev);
ret = create_hw_context(dev_priv->dev, NULL, &ctx);
if (ret != 0)
return (ret);
/* We may need to do things with the shrinker which require us to
* immediately switch back to the default context. This can cause a
* problem as pinning the default context also requires GTT space which
* may not be available. To avoid this we always pin the
* default context.
*/
dev_priv->rings[RCS].default_context = ctx;
ret = i915_gem_object_pin(ctx->obj, CONTEXT_ALIGN, false);
if (ret)
goto err_destroy;
ret = do_switch(ctx);
if (ret)
goto err_unpin;
DRM_DEBUG_DRIVER("Default HW context loaded\n");
return 0;
err_unpin:
i915_gem_object_unpin(ctx->obj);
err_destroy:
do_destroy(ctx);
return ret;
}
int intel_init_ring_buffer(filler_t **readpage)
{
i915_gem_alloc_object(readpage);
return i915_gem_object_pin(readpage);
}
static int do_switch(struct drm_i915_gem_object *from_obj,
struct i915_hw_context *to,
u32 seqno)
{
struct intel_ring_buffer *ring = NULL;
u32 hw_flags = 0;
int ret;
BUG_ON(to == NULL);
BUG_ON(from_obj != NULL && from_obj->pin_count == 0);
ret = i915_gem_object_pin(to->obj, CONTEXT_ALIGN, false);
if (ret)
return ret;
/* 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_obj == to->obj)) /* not yet expected */
hw_flags |= MI_FORCE_RESTORE;
ring = to->ring;
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_obj != NULL) {
from_obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
i915_gem_object_move_to_active(from_obj, ring, seqno);
/* 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 != to->ring);
i915_gem_object_unpin(from_obj);
drm_gem_object_unreference(&from_obj->base);
}
drm_gem_object_reference(&to->obj->base);
ring->last_context_obj = to->obj;
to->is_initialized = true;
return 0;
}
