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/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2019 Intel Corporation
*/
#include "i915_drv.h"
#include "intel_engine.h"
#include "intel_engine_heartbeat.h"
#include "intel_engine_pm.h"
#include "intel_engine_pool.h"
#include "intel_gt.h"
#include "intel_gt_pm.h"
#include "intel_rc6.h"
#include "intel_ring.h"
static int __engine_unpark(struct intel_wakeref *wf)
{
struct intel_engine_cs *engine =
container_of(wf, typeof(*engine), wakeref);
void *map;
GEM_TRACE("%s\n", engine->name);
intel_gt_pm_get(engine->gt);
/* Pin the default state for fast resets from atomic context. */
map = NULL;
if (engine->default_state)
map = i915_gem_object_pin_map(engine->default_state,
I915_MAP_WB);
if (!IS_ERR_OR_NULL(map))
engine->pinned_default_state = map;
if (engine->unpark)
engine->unpark(engine);
intel_engine_unpark_heartbeat(engine);
return 0;
}
#if IS_ENABLED(CONFIG_LOCKDEP)
static inline unsigned long __timeline_mark_lock(struct intel_context *ce)
{
unsigned long flags;
local_irq_save(flags);
mutex_acquire(&ce->timeline->mutex.dep_map, 2, 0, _THIS_IP_);
return flags;
}
static inline void __timeline_mark_unlock(struct intel_context *ce,
unsigned long flags)
{
mutex_release(&ce->timeline->mutex.dep_map, _THIS_IP_);
local_irq_restore(flags);
}
#else
static inline unsigned long __timeline_mark_lock(struct intel_context *ce)
{
return 0;
}
static inline void __timeline_mark_unlock(struct intel_context *ce,
unsigned long flags)
{
}
#endif /* !IS_ENABLED(CONFIG_LOCKDEP) */
static void
__queue_and_release_pm(struct i915_request *rq,
struct intel_timeline *tl,
struct intel_engine_cs *engine)
{
struct intel_gt_timelines *timelines = &engine->gt->timelines;
GEM_TRACE("%s\n", engine->name);
/*
* We have to serialise all potential retirement paths with our
* submission, as we don't want to underflow either the
* engine->wakeref.counter or our timeline->active_count.
*
* Equally, we cannot allow a new submission to start until
* after we finish queueing, nor could we allow that submitter
* to retire us before we are ready!
*/
spin_lock(&timelines->lock);
/* Let intel_gt_retire_requests() retire us (acquired under lock) */
if (!atomic_fetch_inc(&tl->active_count))
list_add_tail(&tl->link, &timelines->active_list);
/* Hand the request over to HW and so engine_retire() */
__i915_request_queue(rq, NULL);
/* Let new submissions commence (and maybe retire this timeline) */
__intel_wakeref_defer_park(&engine->wakeref);
spin_unlock(&timelines->lock);
}
static bool switch_to_kernel_context(struct intel_engine_cs *engine)
{
struct intel_context *ce = engine->kernel_context;
struct i915_request *rq;
unsigned long flags;
bool result = true;
/* Already inside the kernel context, safe to power down. */
if (engine->wakeref_serial == engine->serial)
return true;
/* GPU is pointing to the void, as good as in the kernel context. */
if (intel_gt_is_wedged(engine->gt))
return true;
/*
* Note, we do this without taking the timeline->mutex. We cannot
* as we may be called while retiring the kernel context and so
* already underneath the timeline->mutex. Instead we rely on the
* exclusive property of the __engine_park that prevents anyone
* else from creating a request on this engine. This also requires
* that the ring is empty and we avoid any waits while constructing
* the context, as they assume protection by the timeline->mutex.
* This should hold true as we can only park the engine after
* retiring the last request, thus all rings should be empty and
* all timelines idle.
*
* For unlocking, there are 2 other parties and the GPU who have a
* stake here.
*
* A new gpu user will be waiting on the engine-pm to start their
* engine_unpark. New waiters are predicated on engine->wakeref.count
* and so intel_wakeref_defer_park() acts like a mutex_unlock of the
* engine->wakeref.
*
* The other party is intel_gt_retire_requests(), which is walking the
* list of active timelines looking for completions. Meanwhile as soon
* as we call __i915_request_queue(), the GPU may complete our request.
* Ergo, if we put ourselves on the timelines.active_list
* (se intel_timeline_enter()) before we increment the
* engine->wakeref.count, we may see the request completion and retire
* it causing an undeflow of the engine->wakeref.
*/
flags = __timeline_mark_lock(ce);
GEM_BUG_ON(atomic_read(&ce->timeline->active_count) < 0);
rq = __i915_request_create(ce, GFP_NOWAIT);
if (IS_ERR(rq))
/* Context switch failed, hope for the best! Maybe reset? */
goto out_unlock;
/* Check again on the next retirement. */
engine->wakeref_serial = engine->serial + 1;
i915_request_add_active_barriers(rq);
/* Install ourselves as a preemption barrier */
rq->sched.attr.priority = I915_PRIORITY_BARRIER;
__i915_request_commit(rq);
/* Expose ourselves to the world */
__queue_and_release_pm(rq, ce->timeline, engine);
result = false;
out_unlock:
__timeline_mark_unlock(ce, flags);
return result;
}
static void call_idle_barriers(struct intel_engine_cs *engine)
{
struct llist_node *node, *next;
llist_for_each_safe(node, next, llist_del_all(&engine->barrier_tasks)) {
struct dma_fence_cb *cb =
container_of((struct list_head *)node,
typeof(*cb), node);
cb->func(NULL, cb);
}
}
static int __engine_park(struct intel_wakeref *wf)
{
struct intel_engine_cs *engine =
container_of(wf, typeof(*engine), wakeref);
engine->saturated = 0;
/*
* If one and only one request is completed between pm events,
* we know that we are inside the kernel context and it is
* safe to power down. (We are paranoid in case that runtime
* suspend causes corruption to the active context image, and
* want to avoid that impacting userspace.)
*/
if (!switch_to_kernel_context(engine))
return -EBUSY;
GEM_TRACE("%s\n", engine->name);
call_idle_barriers(engine); /* cleanup after wedging */
intel_engine_park_heartbeat(engine);
intel_engine_disarm_breadcrumbs(engine);
intel_engine_pool_park(&engine->pool);
/* Must be reset upon idling, or we may miss the busy wakeup. */
GEM_BUG_ON(engine->execlists.queue_priority_hint != INT_MIN);
if (engine->park)
engine->park(engine);
if (engine->pinned_default_state) {
i915_gem_object_unpin_map(engine->default_state);
engine->pinned_default_state = NULL;
}
engine->execlists.no_priolist = false;
/* While gt calls i915_vma_parked(), we have to break the lock cycle */
intel_gt_pm_put_async(engine->gt);
return 0;
}
static const struct intel_wakeref_ops wf_ops = {
.get = __engine_unpark,
.put = __engine_park,
};
void intel_engine_init__pm(struct intel_engine_cs *engine)
{
struct intel_runtime_pm *rpm = engine->uncore->rpm;
intel_wakeref_init(&engine->wakeref, rpm, &wf_ops);
intel_engine_init_heartbeat(engine);
}
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftest_engine_pm.c"
#endif
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