From 2246bea6cf773552106d98ab31ba7952c4ddb3f9 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 17 Feb 2017 15:13:00 +0000 Subject: [PATCH] drm/i915: Postpone fake breadcrumb interrupt until real interrupts cease When the timer expires for checking on interrupt processing, check to see if any interrupts arrived within the last time period. If real interrupts are still being delivered, we can be reassured that we haven't missed the final interrupt as the waiter will still be woken. Only once all activity ceases, do we have to worry about the waiter never being woken and so need to install a timer to kick the waiter for a slow arrival of a seqno. Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: http://patchwork.freedesktop.org/patch/msgid/20170217151304.16665-2-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_irq.c | 1 + drivers/gpu/drm/i915/intel_breadcrumbs.c | 22 +++++++++------------- drivers/gpu/drm/i915/intel_ringbuffer.h | 3 ++- 3 files changed, 12 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 0d8ebd147da6..0657ac44a582 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1033,6 +1033,7 @@ static void ironlake_rps_change_irq_handler(struct drm_i915_private *dev_priv) static void notify_ring(struct intel_engine_cs *engine) { + atomic_inc(&engine->irq_count); set_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted); if (intel_engine_wakeup(engine)) trace_i915_gem_request_notify(engine); diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c index 74cb7b91b5db..4395b177493e 100644 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -26,6 +26,11 @@ #include "i915_drv.h" +static unsigned long wait_timeout(void) +{ + return round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES); +} + static void intel_breadcrumbs_hangcheck(unsigned long data) { struct intel_engine_cs *engine = (struct intel_engine_cs *)data; @@ -34,8 +39,9 @@ static void intel_breadcrumbs_hangcheck(unsigned long data) if (!b->irq_enabled) return; - if (time_before(jiffies, b->timeout)) { - mod_timer(&b->hangcheck, b->timeout); + if (b->hangcheck_interrupts != atomic_read(&engine->irq_count)) { + b->hangcheck_interrupts = atomic_read(&engine->irq_count); + mod_timer(&b->hangcheck, wait_timeout()); return; } @@ -55,11 +61,6 @@ static void intel_breadcrumbs_hangcheck(unsigned long data) i915_queue_hangcheck(engine->i915); } -static unsigned long wait_timeout(void) -{ - return round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES); -} - static void intel_breadcrumbs_fake_irq(unsigned long data) { struct intel_engine_cs *engine = (struct intel_engine_cs *)data; @@ -140,8 +141,7 @@ static void __intel_breadcrumbs_enable_irq(struct intel_breadcrumbs *b) i915_queue_hangcheck(i915); } else { /* Ensure we never sleep indefinitely */ - GEM_BUG_ON(!time_after(b->timeout, jiffies)); - mod_timer(&b->hangcheck, b->timeout); + mod_timer(&b->hangcheck, wait_timeout()); } } @@ -258,7 +258,6 @@ 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->timeout = wait_timeout(); b->first_wait = to_wait(next); rcu_assign_pointer(b->irq_seqno_bh, b->first_wait->tsk); /* As there is a delay between reading the current @@ -286,7 +285,6 @@ static bool __intel_engine_add_wait(struct intel_engine_cs *engine, if (first) { GEM_BUG_ON(rb_first(&b->waiters) != &wait->node); - b->timeout = wait_timeout(); b->first_wait = wait; rcu_assign_pointer(b->irq_seqno_bh, wait->tsk); /* After assigning ourselves as the new bottom-half, we must @@ -396,7 +394,6 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine, * the interrupt, or if we have to handle an * exception rather than a seqno completion. */ - b->timeout = wait_timeout(); b->first_wait = to_wait(next); rcu_assign_pointer(b->irq_seqno_bh, b->first_wait->tsk); if (b->first_wait->seqno != wait->seqno) @@ -627,7 +624,6 @@ void intel_engine_reset_breadcrumbs(struct intel_engine_cs *engine) __intel_breadcrumbs_disable_irq(b); if (intel_engine_has_waiter(engine)) { - b->timeout = wait_timeout(); __intel_breadcrumbs_enable_irq(b); if (test_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted)) wake_up_process(b->first_wait->tsk); diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index 4ca5308e12bb..4091c97be6ec 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -213,6 +213,7 @@ struct intel_engine_cs { struct intel_render_state *render_state; + atomic_t irq_count; unsigned long irq_posted; #define ENGINE_IRQ_BREADCRUMB 0 #define ENGINE_IRQ_EXECLIST 1 @@ -245,7 +246,7 @@ struct intel_engine_cs { struct timer_list fake_irq; /* used after a missed interrupt */ struct timer_list hangcheck; /* detect missed interrupts */ - unsigned long timeout; + unsigned int hangcheck_interrupts; bool irq_enabled : 1; bool rpm_wakelock : 1; -- 2.20.1