[Intel-gfx] [RFC] drm/i915: Reduce locking in command submission

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Eliminate six needless spin lock/unlock pairs when writing ELSP.

RFC for now with some #define copy and paste.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Dave Gordon <david.s.gordon at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index a82020e..f2f4a28 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -276,6 +276,10 @@ static uint64_t execlists_ctx_descriptor(struct drm_i915_gem_object *ctx_obj)
 	return desc;
 }
 
+#define __raw_i915_read32(dev_priv__, reg__) readl((dev_priv__)->regs + (reg__))
+#define __raw_i915_write32(dev_priv__, reg__, val__) writel(val__, (dev_priv__)->regs + (reg__))
+#define __raw_posting_read(dev_priv__, reg__) (void)__raw_i915_read32(dev_priv__, reg__)
+
 static void execlists_elsp_write(struct intel_engine_cs *ring,
 				 struct drm_i915_gem_object *ctx_obj0,
 				 struct drm_i915_gem_object *ctx_obj1)
@@ -323,19 +327,17 @@ static void execlists_elsp_write(struct intel_engine_cs *ring,
 			dev_priv->uncore.funcs.force_wake_get(dev_priv,
 							      FORCEWAKE_ALL);
 	}
-	spin_unlock_irqrestore(&dev_priv->uncore.lock, flags);
 
-	I915_WRITE(RING_ELSP(ring), desc[1]);
-	I915_WRITE(RING_ELSP(ring), desc[0]);
-	I915_WRITE(RING_ELSP(ring), desc[3]);
+	__raw_i915_write32(dev_priv, RING_ELSP(ring), desc[1]);
+	__raw_i915_write32(dev_priv, RING_ELSP(ring), desc[0]);
+	__raw_i915_write32(dev_priv, RING_ELSP(ring), desc[3]);
 	/* The context is automatically loaded after the following */
-	I915_WRITE(RING_ELSP(ring), desc[2]);
+	__raw_i915_write32(dev_priv, RING_ELSP(ring), desc[2]);
 
 	/* ELSP is a wo register, so use another nearby reg for posting instead */
-	POSTING_READ(RING_EXECLIST_STATUS(ring));
+	__raw_posting_read(dev_priv, RING_EXECLIST_STATUS(ring));
 
 	/* Release Force Wakeup (see the big comment above). */
-	spin_lock_irqsave(&dev_priv->uncore.lock, flags);
 	if (IS_CHERRYVIEW(dev) || INTEL_INFO(dev)->gen >= 9) {
 		if (--dev_priv->uncore.fw_rendercount == 0)
 			dev_priv->uncore.funcs.force_wake_put(dev_priv,
-- 
2.1.1