drm/i915/gt: Only disable interrupts for the timeline lock on !force-…

…threaded

According to commit
    d677392 ("drm/i915/gt: Mark up the nested engine-pm timeline lock as irqsafe")

the intrrupts are disabled the code may be called from an interrupt
handler and from preemptible context.
With `force_irqthreads' set the timeline mutex is never observed in IRQ
context so it is not neede to disable interrupts.

Disable only interrupts if not in `force_irqthreads' mode.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/gpu/drm/i915/gt/intel_engine_pm.c

@@ -84,9 +84,10 @@ static int __engine_unpark(struct intel_wakeref *wf)
 
 static unsigned long __timeline_mark_lock(struct intel_context *ce)
 {
-	unsigned long flags;
+	unsigned long flags = 0;
 
-	local_irq_save(flags);
+	if (!force_irqthreads())
+		local_irq_save(flags);
 	mutex_acquire(&ce->timeline->mutex.dep_map, 2, 0, _THIS_IP_);
 
 	return flags;
@@ -96,7 +97,8 @@ static void __timeline_mark_unlock(struct intel_context *ce,
 				   unsigned long flags)
 {
 	mutex_release(&ce->timeline->mutex.dep_map, _THIS_IP_);
-	local_irq_restore(flags);
+	if (!force_irqthreads())
+		local_irq_restore(flags);
 }
 
 #else