drm/i915/icl: Ringbuffer interrupt handling

On Gen11 interrupt masks need to be clear to allow C6 entry.
We keep them all enabled knowing that we generate extra
interrupts.

v2: Rebase.
v3: Remove gen 11 extra check in logical_render_ring_init.
v4: Rebase fixes.
v5: Rebase/refactor.
v6: Rebase.
v7: Rebase.
v8: Update comment and commit message (Daniele)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180302161501.28594-1-mika.kuoppala@linux.intel.com

drivers/gpu/drm/i915/intel_breadcrumbs.c

@@ -168,17 +168,21 @@ static void irq_enable(struct intel_engine_cs *engine)
 	set_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted);
 
 	/* Caller disables interrupts */
+	if (engine->irq_enable) {
 		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 */
+	if (engine->irq_disable) {
 		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)

drivers/gpu/drm/i915/intel_lrc.c

@@ -2037,8 +2037,17 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
 
 	engine->set_default_submission = execlists_set_default_submission;
 
+	if (INTEL_GEN(engine->i915) < 11) {
 		engine->irq_enable = gen8_logical_ring_enable_irq;
 		engine->irq_disable = gen8_logical_ring_disable_irq;
+	} else {
+		/*
+		 * TODO: On Gen11 interrupt masks need to be clear
+		 * to allow C6 entry. Keep interrupts enabled at
+		 * and take the hit of generating extra interrupts
+		 * until a more refined solution exists.
+		 */
+	}
 	engine->emit_bb_start = gen8_emit_bb_start;
 }