Refactor the common task of updating the first_waiter, serialised with
the interrupt handler. When we update the first_waiter, we also need to
wakeup the new bottom-half in order to complete the actions that we may
have delegated to it (such as checking the irq-seqno coherency or waking
up other lower priority concurrent waiters).
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_breadcrumbs.c | 48 ++++++++++++--------------------
1 file changed, 18 insertions(+), 30 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index 235d4645a5cf..2b26f84480cc 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -287,6 +287,22 @@ static inline void __intel_breadcrumbs_finish(struct intel_breadcrumbs *b,
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;
+
+ GEM_BUG_ON(!b->irq_armed);
+ b->first_wait = to_wait(next);
+
+ /* 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)
{
@@ -357,21 +373,7 @@ static bool __intel_engine_add_wait(struct intel_engine_cs *engine,
GEM_BUG_ON(!next && !first);
if (next && next != &wait->node) {
GEM_BUG_ON(first);
- b->first_wait = to_wait(next);
- /* As there is a delay between reading the current
- * seqno, processing the completed tasks and selecting
- * the next waiter, we may have missed the interrupt
- * and so need for the next bottom-half to wakeup.
- *
- * Also as we enable the IRQ, we may miss the
- * interrupt for that seqno, so we have to wake up
- * the next bottom-half in order to do a coherent check
- * in case the seqno passed.
- */
- __intel_breadcrumbs_enable_irq(b);
- if (test_bit(ENGINE_IRQ_BREADCRUMB,
- &engine->irq_posted))
- wake_up_process(to_wait(next)->tsk);
+ __intel_breadcrumbs_next(engine, next);
}
do {
@@ -473,21 +475,7 @@ static void __intel_engine_remove_wait(struct intel_engine_cs *engine,
}
}
- if (next) {
- /* In our haste, we may have completed the first waiter
- * before we enabled the interrupt. Do so now as we
- * have a second waiter for a future seqno. Afterwards,
- * we have to wake up that waiter in case we missed
- * the interrupt, or if we have to handle an
- * exception rather than a seqno completion.
- */
- b->first_wait = to_wait(next);
- if (b->first_wait->seqno != wait->seqno)
- __intel_breadcrumbs_enable_irq(b);
- wake_up_process(b->first_wait->tsk);
- } else {
- b->first_wait = NULL;
- }
+ __intel_breadcrumbs_next(engine, next);
} else {
GEM_BUG_ON(rb_first(&b->waiters) == &wait->node);
}
--
2.11.0
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