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-rw-r--r--debian/patches-rt/0264-drm-i915-Don-t-disable-interrupts-independently-of-t.patch51
1 files changed, 51 insertions, 0 deletions
diff --git a/debian/patches-rt/0264-drm-i915-Don-t-disable-interrupts-independently-of-t.patch b/debian/patches-rt/0264-drm-i915-Don-t-disable-interrupts-independently-of-t.patch
new file mode 100644
index 000000000..e95fb336e
--- /dev/null
+++ b/debian/patches-rt/0264-drm-i915-Don-t-disable-interrupts-independently-of-t.patch
@@ -0,0 +1,51 @@
+From 31ae53586975d39dd03dabf5c944b498dcc73289 Mon Sep 17 00:00:00 2001
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Wed, 10 Apr 2019 11:01:37 +0200
+Subject: [PATCH 264/347] drm/i915: Don't disable interrupts independently of
+ the lock
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
+
+The locks (timeline->lock and rq->lock) need to be taken with disabled
+interrupts. This is done in __retire_engine_request() by disabling the
+interrupts independently of the locks itself.
+While local_irq_disable()+spin_lock() equals spin_lock_irq() on vanilla
+it does not on RT. Also, it is not obvious if there is a special reason
+to why the interrupts are disabled independently of the lock.
+
+Enable/disable interrupts as part of the locking instruction.
+
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+---
+ drivers/gpu/drm/i915/i915_request.c | 8 ++------
+ 1 file changed, 2 insertions(+), 6 deletions(-)
+
+diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
+index 5c2c93cbab12..7124510b9131 100644
+--- a/drivers/gpu/drm/i915/i915_request.c
++++ b/drivers/gpu/drm/i915/i915_request.c
+@@ -356,9 +356,7 @@ static void __retire_engine_request(struct intel_engine_cs *engine,
+
+ GEM_BUG_ON(!i915_request_completed(rq));
+
+- local_irq_disable();
+-
+- spin_lock(&engine->timeline.lock);
++ spin_lock_irq(&engine->timeline.lock);
+ GEM_BUG_ON(!list_is_first(&rq->link, &engine->timeline.requests));
+ list_del_init(&rq->link);
+ spin_unlock(&engine->timeline.lock);
+@@ -372,9 +370,7 @@ static void __retire_engine_request(struct intel_engine_cs *engine,
+ GEM_BUG_ON(!atomic_read(&rq->i915->gt_pm.rps.num_waiters));
+ atomic_dec(&rq->i915->gt_pm.rps.num_waiters);
+ }
+- spin_unlock(&rq->lock);
+-
+- local_irq_enable();
++ spin_unlock_irq(&rq->lock);
+
+ /*
+ * The backing object for the context is done after switching to the
+--
+2.36.1
+