blob: 5095c095da042ce0e1ace79e5790e8e4cfa82276 [file] [log] [blame]
/*
* Copyright © 2015 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
*/
#include <linux/kthread.h>
#include <uapi/linux/sched/types.h>
#include "i915_drv.h"
static unsigned int __intel_breadcrumbs_wakeup(struct intel_breadcrumbs *b)
{
struct intel_wait *wait;
unsigned int result = 0;
lockdep_assert_held(&b->irq_lock);
wait = b->irq_wait;
if (wait) {
result = ENGINE_WAKEUP_WAITER;
if (wake_up_process(wait->tsk))
result |= ENGINE_WAKEUP_ASLEEP;
}
return result;
}
unsigned int intel_engine_wakeup(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
unsigned long flags;
unsigned int result;
spin_lock_irqsave(&b->irq_lock, flags);
result = __intel_breadcrumbs_wakeup(b);
spin_unlock_irqrestore(&b->irq_lock, flags);
return result;
}
static unsigned long wait_timeout(void)
{
return round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES);
}
static noinline void missed_breadcrumb(struct intel_engine_cs *engine)
{
DRM_DEBUG_DRIVER("%s missed breadcrumb at %pF, irq posted? %s, current seqno=%x, last=%x\n",
engine->name, __builtin_return_address(0),
yesno(test_bit(ENGINE_IRQ_BREADCRUMB,
&engine->irq_posted)),
intel_engine_get_seqno(engine),
intel_engine_last_submit(engine));
set_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings);
}
static void intel_breadcrumbs_hangcheck(unsigned long data)
{
struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
struct intel_breadcrumbs *b = &engine->breadcrumbs;
if (!b->irq_armed)
return;
if (b->hangcheck_interrupts != atomic_read(&engine->irq_count)) {
b->hangcheck_interrupts = atomic_read(&engine->irq_count);
mod_timer(&b->hangcheck, wait_timeout());
return;
}
/* We keep the hangcheck timer alive until we disarm the irq, even
* if there are no waiters at present.
*
* If the waiter was currently running, assume it hasn't had a chance
* to process the pending interrupt (e.g, low priority task on a loaded
* system) and wait until it sleeps before declaring a missed interrupt.
*
* If the waiter was asleep (and not even pending a wakeup), then we
* must have missed an interrupt as the GPU has stopped advancing
* but we still have a waiter. Assuming all batches complete within
* DRM_I915_HANGCHECK_JIFFIES [1.5s]!
*/
if (intel_engine_wakeup(engine) & ENGINE_WAKEUP_ASLEEP) {
missed_breadcrumb(engine);
mod_timer(&engine->breadcrumbs.fake_irq, jiffies + 1);
} else {
mod_timer(&b->hangcheck, wait_timeout());
}
}
static void intel_breadcrumbs_fake_irq(unsigned long data)
{
struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
struct intel_breadcrumbs *b = &engine->breadcrumbs;
/* The timer persists in case we cannot enable interrupts,
* or if we have previously seen seqno/interrupt incoherency
* ("missed interrupt" syndrome, better known as a "missed breadcrumb").
* Here the worker will wake up every jiffie in order to kick the
* oldest waiter to do the coherent seqno check.
*/
spin_lock_irq(&b->irq_lock);
if (!__intel_breadcrumbs_wakeup(b))
__intel_engine_disarm_breadcrumbs(engine);
spin_unlock_irq(&b->irq_lock);
if (!b->irq_armed)
return;
mod_timer(&b->fake_irq, jiffies + 1);
/* Ensure that even if the GPU hangs, we get woken up.
*
* However, note that if no one is waiting, we never notice
* a gpu hang. Eventually, we will have to wait for a resource
* held by the GPU and so trigger a hangcheck. In the most
* pathological case, this will be upon memory starvation! To
* prevent this, we also queue the hangcheck from the retire
* worker.
*/
i915_queue_hangcheck(engine->i915);
}
static void irq_enable(struct intel_engine_cs *engine)
{
/* Enabling the IRQ may miss the generation of the interrupt, but
* we still need to force the barrier before reading the seqno,
* just in case.
*/
set_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted);
/* Caller disables interrupts */
spin_lock(&engine->i915->irq_lock);
engine->irq_enable(engine);
spin_unlock(&engine->i915->irq_lock);
}
static void irq_disable(struct intel_engine_cs *engine)
{
/* Caller disables interrupts */
spin_lock(&engine->i915->irq_lock);
engine->irq_disable(engine);
spin_unlock(&engine->i915->irq_lock);
}
void __intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
lockdep_assert_held(&b->irq_lock);
GEM_BUG_ON(b->irq_wait);
if (b->irq_enabled) {
irq_disable(engine);
b->irq_enabled = false;
}
b->irq_armed = false;
}
void intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
struct intel_wait *wait, *n, *first;
if (!b->irq_armed)
return;
/* We only disarm the irq when we are idle (all requests completed),
* so if the bottom-half remains asleep, it missed the request
* completion.
*/
spin_lock_irq(&b->rb_lock);
spin_lock(&b->irq_lock);
first = fetch_and_zero(&b->irq_wait);
__intel_engine_disarm_breadcrumbs(engine);
spin_unlock(&b->irq_lock);
rbtree_postorder_for_each_entry_safe(wait, n, &b->waiters, node) {
RB_CLEAR_NODE(&wait->node);
if (wake_up_process(wait->tsk) && wait == first)
missed_breadcrumb(engine);
}
b->waiters = RB_ROOT;
spin_unlock_irq(&b->rb_lock);
}
static bool use_fake_irq(const struct intel_breadcrumbs *b)
{
const struct intel_engine_cs *engine =
container_of(b, struct intel_engine_cs, breadcrumbs);
if (!test_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings))
return false;
/* Only start with the heavy weight fake irq timer if we have not
* seen any interrupts since enabling it the first time. If the
* interrupts are still arriving, it means we made a mistake in our
* engine->seqno_barrier(), a timing error that should be transient
* and unlikely to reoccur.
*/
return atomic_read(&engine->irq_count) == b->hangcheck_interrupts;
}
static void enable_fake_irq(struct intel_breadcrumbs *b)
{
/* Ensure we never sleep indefinitely */
if (!b->irq_enabled || use_fake_irq(b))
mod_timer(&b->fake_irq, jiffies + 1);
else
mod_timer(&b->hangcheck, wait_timeout());
}
static bool __intel_breadcrumbs_enable_irq(struct intel_breadcrumbs *b)
{
struct intel_engine_cs *engine =
container_of(b, struct intel_engine_cs, breadcrumbs);
struct drm_i915_private *i915 = engine->i915;
lockdep_assert_held(&b->irq_lock);
if (b->irq_armed)
return false;
/* The breadcrumb irq will be disarmed on the interrupt after the
* waiters are signaled. This gives us a single interrupt window in
* which we can add a new waiter and avoid the cost of re-enabling
* the irq.
*/
b->irq_armed = true;
GEM_BUG_ON(b->irq_enabled);
if (I915_SELFTEST_ONLY(b->mock)) {
/* For our mock objects we want to avoid interaction
* with the real hardware (which is not set up). So
* we simply pretend we have enabled the powerwell
* and the irq, and leave it up to the mock
* implementation to call intel_engine_wakeup()
* itself when it wants to simulate a user interrupt,
*/
return true;
}
/* Since we are waiting on a request, the GPU should be busy
* and should have its own rpm reference. This is tracked
* by i915->gt.awake, we can forgo holding our own wakref
* for the interrupt as before i915->gt.awake is released (when
* the driver is idle) we disarm the breadcrumbs.
*/
/* No interrupts? Kick the waiter every jiffie! */
if (intel_irqs_enabled(i915)) {
if (!test_bit(engine->id, &i915->gpu_error.test_irq_rings))
irq_enable(engine);
b->irq_enabled = true;
}
enable_fake_irq(b);
return true;
}
static inline struct intel_wait *to_wait(struct rb_node *node)
{
return rb_entry(node, struct intel_wait, node);
}
static inline void __intel_breadcrumbs_finish(struct intel_breadcrumbs *b,
struct intel_wait *wait)
{
lockdep_assert_held(&b->rb_lock);
GEM_BUG_ON(b->irq_wait == wait);
/* This request is completed, so remove it from the tree, mark it as
* complete, and *then* wake up the associated task. N.B. when the
* task wakes up, it will find the empty rb_node, discern that it
* has already been removed from the tree and skip the serialisation
* of the b->rb_lock and b->irq_lock. This means that the destruction
* of the intel_wait is not serialised with the interrupt handler
* by the waiter - it must instead be serialised by the caller.
*/
rb_erase(&wait->node, &b->waiters);
RB_CLEAR_NODE(&wait->node);
wake_up_process(wait->tsk); /* implicit smp_wmb() */
}
static inline void __intel_breadcrumbs_next(struct intel_engine_cs *engine,
struct rb_node *next)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
spin_lock(&b->irq_lock);
GEM_BUG_ON(!b->irq_armed);
GEM_BUG_ON(!b->irq_wait);
b->irq_wait = to_wait(next);
spin_unlock(&b->irq_lock);
/* We always wake up the next waiter that takes over as the bottom-half
* as we may delegate not only the irq-seqno barrier to the next waiter
* but also the task of waking up concurrent waiters.
*/
if (next)
wake_up_process(to_wait(next)->tsk);
}
static bool __intel_engine_add_wait(struct intel_engine_cs *engine,
struct intel_wait *wait)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
struct rb_node **p, *parent, *completed;
bool first, armed;
u32 seqno;
/* Insert the request into the retirement ordered list
* of waiters by walking the rbtree. If we are the oldest
* seqno in the tree (the first to be retired), then
* set ourselves as the bottom-half.
*
* As we descend the tree, prune completed branches since we hold the
* spinlock we know that the first_waiter must be delayed and can
* reduce some of the sequential wake up latency if we take action
* ourselves and wake up the completed tasks in parallel. Also, by
* removing stale elements in the tree, we may be able to reduce the
* ping-pong between the old bottom-half and ourselves as first-waiter.
*/
armed = false;
first = true;
parent = NULL;
completed = NULL;
seqno = intel_engine_get_seqno(engine);
/* If the request completed before we managed to grab the spinlock,
* return now before adding ourselves to the rbtree. We let the
* current bottom-half handle any pending wakeups and instead
* try and get out of the way quickly.
*/
if (i915_seqno_passed(seqno, wait->seqno)) {
RB_CLEAR_NODE(&wait->node);
return first;
}
p = &b->waiters.rb_node;
while (*p) {
parent = *p;
if (wait->seqno == to_wait(parent)->seqno) {
/* We have multiple waiters on the same seqno, select
* the highest priority task (that with the smallest
* task->prio) to serve as the bottom-half for this
* group.
*/
if (wait->tsk->prio > to_wait(parent)->tsk->prio) {
p = &parent->rb_right;
first = false;
} else {
p = &parent->rb_left;
}
} else if (i915_seqno_passed(wait->seqno,
to_wait(parent)->seqno)) {
p = &parent->rb_right;
if (i915_seqno_passed(seqno, to_wait(parent)->seqno))
completed = parent;
else
first = false;
} else {
p = &parent->rb_left;
}
}
rb_link_node(&wait->node, parent, p);
rb_insert_color(&wait->node, &b->waiters);
if (first) {
spin_lock(&b->irq_lock);
b->irq_wait = wait;
/* After assigning ourselves as the new bottom-half, we must
* perform a cursory check to prevent a missed interrupt.
* Either we miss the interrupt whilst programming the hardware,
* or if there was a previous waiter (for a later seqno) they
* may be woken instead of us (due to the inherent race
* in the unlocked read of b->irq_seqno_bh in the irq handler)
* and so we miss the wake up.
*/
armed = __intel_breadcrumbs_enable_irq(b);
spin_unlock(&b->irq_lock);
}
if (completed) {
/* Advance the bottom-half (b->irq_wait) before we wake up
* the waiters who may scribble over their intel_wait
* just as the interrupt handler is dereferencing it via
* b->irq_wait.
*/
if (!first) {
struct rb_node *next = rb_next(completed);
GEM_BUG_ON(next == &wait->node);
__intel_breadcrumbs_next(engine, next);
}
do {
struct intel_wait *crumb = to_wait(completed);
completed = rb_prev(completed);
__intel_breadcrumbs_finish(b, crumb);
} while (completed);
}
GEM_BUG_ON(!b->irq_wait);
GEM_BUG_ON(!b->irq_armed);
GEM_BUG_ON(rb_first(&b->waiters) != &b->irq_wait->node);
return armed;
}
bool intel_engine_add_wait(struct intel_engine_cs *engine,
struct intel_wait *wait)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
bool armed;
spin_lock_irq(&b->rb_lock);
armed = __intel_engine_add_wait(engine, wait);
spin_unlock_irq(&b->rb_lock);
if (armed)
return armed;
/* Make the caller recheck if its request has already started. */
return i915_seqno_passed(intel_engine_get_seqno(engine),
wait->seqno - 1);
}
static inline bool chain_wakeup(struct rb_node *rb, int priority)
{
return rb && to_wait(rb)->tsk->prio <= priority;
}
static inline int wakeup_priority(struct intel_breadcrumbs *b,
struct task_struct *tsk)
{
if (tsk == b->signaler)
return INT_MIN;
else
return tsk->prio;
}
static void __intel_engine_remove_wait(struct intel_engine_cs *engine,
struct intel_wait *wait)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
lockdep_assert_held(&b->rb_lock);
if (RB_EMPTY_NODE(&wait->node))
goto out;
if (b->irq_wait == wait) {
const int priority = wakeup_priority(b, wait->tsk);
struct rb_node *next;
/* We are the current bottom-half. Find the next candidate,
* the first waiter in the queue on the remaining oldest
* request. As multiple seqnos may complete in the time it
* takes us to wake up and find the next waiter, we have to
* wake up that waiter for it to perform its own coherent
* completion check.
*/
next = rb_next(&wait->node);
if (chain_wakeup(next, priority)) {
/* If the next waiter is already complete,
* wake it up and continue onto the next waiter. So
* if have a small herd, they will wake up in parallel
* rather than sequentially, which should reduce
* the overall latency in waking all the completed
* clients.
*
* However, waking up a chain adds extra latency to
* the first_waiter. This is undesirable if that
* waiter is a high priority task.
*/
u32 seqno = intel_engine_get_seqno(engine);
while (i915_seqno_passed(seqno, to_wait(next)->seqno)) {
struct rb_node *n = rb_next(next);
__intel_breadcrumbs_finish(b, to_wait(next));
next = n;
if (!chain_wakeup(next, priority))
break;
}
}
__intel_breadcrumbs_next(engine, next);
} else {
GEM_BUG_ON(rb_first(&b->waiters) == &wait->node);
}
GEM_BUG_ON(RB_EMPTY_NODE(&wait->node));
rb_erase(&wait->node, &b->waiters);
out:
GEM_BUG_ON(b->irq_wait == wait);
GEM_BUG_ON(rb_first(&b->waiters) !=
(b->irq_wait ? &b->irq_wait->node : NULL));
}
void intel_engine_remove_wait(struct intel_engine_cs *engine,
struct intel_wait *wait)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
/* Quick check to see if this waiter was already decoupled from
* the tree by the bottom-half to avoid contention on the spinlock
* by the herd.
*/
if (RB_EMPTY_NODE(&wait->node)) {
GEM_BUG_ON(READ_ONCE(b->irq_wait) == wait);
return;
}
spin_lock_irq(&b->rb_lock);
__intel_engine_remove_wait(engine, wait);
spin_unlock_irq(&b->rb_lock);
}
static bool signal_complete(const struct drm_i915_gem_request *request)
{
if (!request)
return false;
/*
* Carefully check if the request is complete, giving time for the
* seqno to be visible or if the GPU hung.
*/
return __i915_request_irq_complete(request);
}
static struct drm_i915_gem_request *to_signaler(struct rb_node *rb)
{
return rb_entry(rb, struct drm_i915_gem_request, signaling.node);
}
static void signaler_set_rtpriority(void)
{
struct sched_param param = { .sched_priority = 1 };
sched_setscheduler_nocheck(current, SCHED_FIFO, &param);
}
static int intel_breadcrumbs_signaler(void *arg)
{
struct intel_engine_cs *engine = arg;
struct intel_breadcrumbs *b = &engine->breadcrumbs;
struct drm_i915_gem_request *request;
/* Install ourselves with high priority to reduce signalling latency */
signaler_set_rtpriority();
do {
bool do_schedule = true;
set_current_state(TASK_INTERRUPTIBLE);
/* We are either woken up by the interrupt bottom-half,
* or by a client adding a new signaller. In both cases,
* the GPU seqno may have advanced beyond our oldest signal.
* If it has, propagate the signal, remove the waiter and
* check again with the next oldest signal. Otherwise we
* need to wait for a new interrupt from the GPU or for
* a new client.
*/
rcu_read_lock();
request = rcu_dereference(b->first_signal);
if (request)
request = i915_gem_request_get_rcu(request);
rcu_read_unlock();
if (signal_complete(request)) {
if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
&request->fence.flags)) {
local_bh_disable();
dma_fence_signal(&request->fence);
GEM_BUG_ON(!i915_gem_request_completed(request));
local_bh_enable(); /* kick start the tasklets */
}
spin_lock_irq(&b->rb_lock);
/* Wake up all other completed waiters and select the
* next bottom-half for the next user interrupt.
*/
__intel_engine_remove_wait(engine,
&request->signaling.wait);
/* Find the next oldest signal. Note that as we have
* not been holding the lock, another client may
* have installed an even older signal than the one
* we just completed - so double check we are still
* the oldest before picking the next one.
*/
if (request == rcu_access_pointer(b->first_signal)) {
struct rb_node *rb =
rb_next(&request->signaling.node);
rcu_assign_pointer(b->first_signal,
rb ? to_signaler(rb) : NULL);
}
rb_erase(&request->signaling.node, &b->signals);
RB_CLEAR_NODE(&request->signaling.node);
spin_unlock_irq(&b->rb_lock);
i915_gem_request_put(request);
/* If the engine is saturated we may be continually
* processing completed requests. This angers the
* NMI watchdog if we never let anything else
* have access to the CPU. Let's pretend to be nice
* and relinquish the CPU if we burn through the
* entire RT timeslice!
*/
do_schedule = need_resched();
}
if (unlikely(do_schedule)) {
DEFINE_WAIT(exec);
if (kthread_should_park())
kthread_parkme();
if (kthread_should_stop()) {
GEM_BUG_ON(request);
break;
}
if (request)
add_wait_queue(&request->execute, &exec);
schedule();
if (request)
remove_wait_queue(&request->execute, &exec);
}
i915_gem_request_put(request);
} while (1);
__set_current_state(TASK_RUNNING);
return 0;
}
void intel_engine_enable_signaling(struct drm_i915_gem_request *request,
bool wakeup)
{
struct intel_engine_cs *engine = request->engine;
struct intel_breadcrumbs *b = &engine->breadcrumbs;
u32 seqno;
/* Note that we may be called from an interrupt handler on another
* device (e.g. nouveau signaling a fence completion causing us
* to submit a request, and so enable signaling). As such,
* we need to make sure that all other users of b->rb_lock protect
* against interrupts, i.e. use spin_lock_irqsave.
*/
/* locked by dma_fence_enable_sw_signaling() (irqsafe fence->lock) */
GEM_BUG_ON(!irqs_disabled());
lockdep_assert_held(&request->lock);
seqno = i915_gem_request_global_seqno(request);
if (!seqno)
return;
request->signaling.wait.tsk = b->signaler;
request->signaling.wait.request = request;
request->signaling.wait.seqno = seqno;
i915_gem_request_get(request);
spin_lock(&b->rb_lock);
/* First add ourselves into the list of waiters, but register our
* bottom-half as the signaller thread. As per usual, only the oldest
* waiter (not just signaller) is tasked as the bottom-half waking
* up all completed waiters after the user interrupt.
*
* If we are the oldest waiter, enable the irq (after which we
* must double check that the seqno did not complete).
*/
wakeup &= __intel_engine_add_wait(engine, &request->signaling.wait);
if (!__i915_gem_request_completed(request, seqno)) {
struct rb_node *parent, **p;
bool first;
/* Now insert ourselves into the retirement ordered list of
* signals on this engine. We track the oldest seqno as that
* will be the first signal to complete.
*/
parent = NULL;
first = true;
p = &b->signals.rb_node;
while (*p) {
parent = *p;
if (i915_seqno_passed(seqno,
to_signaler(parent)->signaling.wait.seqno)) {
p = &parent->rb_right;
first = false;
} else {
p = &parent->rb_left;
}
}
rb_link_node(&request->signaling.node, parent, p);
rb_insert_color(&request->signaling.node, &b->signals);
if (first)
rcu_assign_pointer(b->first_signal, request);
} else {
__intel_engine_remove_wait(engine, &request->signaling.wait);
i915_gem_request_put(request);
wakeup = false;
}
spin_unlock(&b->rb_lock);
if (wakeup)
wake_up_process(b->signaler);
}
void intel_engine_cancel_signaling(struct drm_i915_gem_request *request)
{
struct intel_engine_cs *engine = request->engine;
struct intel_breadcrumbs *b = &engine->breadcrumbs;
GEM_BUG_ON(!irqs_disabled());
lockdep_assert_held(&request->lock);
GEM_BUG_ON(!request->signaling.wait.seqno);
spin_lock(&b->rb_lock);
if (!RB_EMPTY_NODE(&request->signaling.node)) {
if (request == rcu_access_pointer(b->first_signal)) {
struct rb_node *rb =
rb_next(&request->signaling.node);
rcu_assign_pointer(b->first_signal,
rb ? to_signaler(rb) : NULL);
}
rb_erase(&request->signaling.node, &b->signals);
RB_CLEAR_NODE(&request->signaling.node);
i915_gem_request_put(request);
}
__intel_engine_remove_wait(engine, &request->signaling.wait);
spin_unlock(&b->rb_lock);
request->signaling.wait.seqno = 0;
}
int intel_engine_init_breadcrumbs(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
struct task_struct *tsk;
spin_lock_init(&b->rb_lock);
spin_lock_init(&b->irq_lock);
setup_timer(&b->fake_irq,
intel_breadcrumbs_fake_irq,
(unsigned long)engine);
setup_timer(&b->hangcheck,
intel_breadcrumbs_hangcheck,
(unsigned long)engine);
/* Spawn a thread to provide a common bottom-half for all signals.
* As this is an asynchronous interface we cannot steal the current
* task for handling the bottom-half to the user interrupt, therefore
* we create a thread to do the coherent seqno dance after the
* interrupt and then signal the waitqueue (via the dma-buf/fence).
*/
tsk = kthread_run(intel_breadcrumbs_signaler, engine,
"i915/signal:%d", engine->id);
if (IS_ERR(tsk))
return PTR_ERR(tsk);
b->signaler = tsk;
return 0;
}
static void cancel_fake_irq(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
del_timer_sync(&b->hangcheck);
del_timer_sync(&b->fake_irq);
clear_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings);
}
void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
cancel_fake_irq(engine);
spin_lock_irq(&b->irq_lock);
if (b->irq_enabled)
irq_enable(engine);
else
irq_disable(engine);
/* We set the IRQ_BREADCRUMB bit when we enable the irq presuming the
* GPU is active and may have already executed the MI_USER_INTERRUPT
* before the CPU is ready to receive. However, the engine is currently
* idle (we haven't started it yet), there is no possibility for a
* missed interrupt as we enabled the irq and so we can clear the
* immediate wakeup (until a real interrupt arrives for the waiter).
*/
clear_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted);
if (b->irq_armed)
enable_fake_irq(b);
spin_unlock_irq(&b->irq_lock);
}
void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
/* The engines should be idle and all requests accounted for! */
WARN_ON(READ_ONCE(b->irq_wait));
WARN_ON(!RB_EMPTY_ROOT(&b->waiters));
WARN_ON(rcu_access_pointer(b->first_signal));
WARN_ON(!RB_EMPTY_ROOT(&b->signals));
if (!IS_ERR_OR_NULL(b->signaler))
kthread_stop(b->signaler);
cancel_fake_irq(engine);
}
bool intel_breadcrumbs_busy(struct intel_engine_cs *engine)
{
struct intel_breadcrumbs *b = &engine->breadcrumbs;
bool busy = false;
spin_lock_irq(&b->rb_lock);
if (b->irq_wait) {
wake_up_process(b->irq_wait->tsk);
busy = true;
}
if (rcu_access_pointer(b->first_signal)) {
wake_up_process(b->signaler);
busy = true;
}
spin_unlock_irq(&b->rb_lock);
return busy;
}
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/intel_breadcrumbs.c"
#endif