[Intel-gfx] [PATCH 50/70] drm/i915: The argument for postfix is redundant

[Chris Wilson]

We are conservative on the amount of free space available in the ring to
avoid overruning the potential MI_INTERRUPT after the seqno write.
Further undermining the justification for the change was that it was
applied incorrectly.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h         | 14 ++------------
 drivers/gpu/drm/i915/i915_gem.c         |  9 +--------
 drivers/gpu/drm/i915/i915_gpu_error.c   |  2 +-
 drivers/gpu/drm/i915/intel_dvo.c        |  2 +-
 drivers/gpu/drm/i915/intel_lrc.c        |  8 +++-----
 drivers/gpu/drm/i915/intel_ringbuffer.c |  2 +-
 6 files changed, 9 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c710a9ea1458..4b46c5b5eb44 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2074,18 +2074,8 @@ struct drm_i915_gem_request {
 	/** GEM sequence number associated with this request. */
 	uint32_t seqno;
 
-	/** Position in the ringbuffer of the start of the request */
-	u32 head;
-
-	/**
-	 * Position in the ringbuffer of the start of the postfix.
-	 * This is required to calculate the maximum available ringbuffer
-	 * space without overwriting the postfix.
-	 */
-	 u32 postfix;
-
-	/** Position in the ringbuffer of the end of the whole request */
-	u32 tail;
+	/** Position in the ringbuffer of the request */
+	u32 head, tail;
 
 	/**
 	 * Context and ring buffer related to this request
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 729c7fa02e12..d9b5bf4f1f21 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1359,7 +1359,7 @@ void i915_gem_request_retire(struct drm_i915_gem_request *request)
 	 * Note this requires that we are always called in request
 	 * completion order.
 	 */
-	request->ringbuf->last_retired_head = request->postfix;
+	request->ringbuf->last_retired_head = request->tail;
 
 	list_del_init(&request->list);
 	i915_gem_request_remove_from_client(request);
@@ -2495,13 +2495,6 @@ int __i915_add_request(struct intel_engine_cs *ring,
 			return ret;
 	}
 
-	/* Record the position of the start of the request so that
-	 * should we detect the updated seqno part-way through the
-	 * GPU processing the request, we never over-estimate the
-	 * position of the head.
-	 */
-	request->postfix = intel_ring_get_tail(ringbuf);
-
 	if (i915.enable_execlists) {
 		ret = ring->emit_request(ringbuf, request);
 		if (ret)
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 8832f1b2a495..b7a00e464ba4 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1072,7 +1072,7 @@ static void i915_gem_record_rings(struct drm_device *dev,
 			erq = &error->ring[i].requests[count++];
 			erq->seqno = request->seqno;
 			erq->jiffies = request->emitted_jiffies;
-			erq->tail = request->postfix;
+			erq->tail = request->tail;
 		}
 	}
 }
diff --git a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c
index 9a27ec7100ef..f45caa6af7d2 100644
--- a/drivers/gpu/drm/i915/intel_dvo.c
+++ b/drivers/gpu/drm/i915/intel_dvo.c
@@ -496,7 +496,7 @@ void intel_dvo_init(struct drm_device *dev)
 		int gpio;
 		bool dvoinit;
 		enum pipe pipe;
-		uint32_t dpll[2];
+		uint32_t dpll[I915_MAX_PIPES];
 
 		/* Allow the I2C driver info to specify the GPIO to be used in
 		 * special cases, but otherwise default to what's defined
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index a62ffaa45bd1..b3ca88ff88eb 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -409,7 +409,6 @@ void intel_lrc_irq_handler(struct intel_engine_cs *ring)
 
 static int execlists_context_queue(struct intel_engine_cs *ring,
 				   struct intel_context *to,
-				   u32 tail,
 				   struct drm_i915_gem_request *request)
 {
 	if (WARN_ON(request == NULL))
@@ -421,8 +420,6 @@ static int execlists_context_queue(struct intel_engine_cs *ring,
 	i915_gem_request_reference(request);
 	WARN_ON(to != request->ctx);
 
-	request->tail = tail;
-
 	spin_lock_irq(&ring->execlist_lock);
 
 	list_add_tail(&request->execlist_link, &ring->execlist_queue);
@@ -574,7 +571,7 @@ static int logical_ring_wait_for_space(struct intel_ringbuffer *ringbuf,
 			continue;
 
 		/* Would completion of this request free enough space? */
-		space = __intel_ring_space(request->postfix, ringbuf->tail,
+		space = __intel_ring_space(request->tail, ringbuf->tail,
 					   ringbuf->size);
 		if (space >= bytes)
 			break;
@@ -608,11 +605,12 @@ intel_logical_ring_advance_and_submit(struct intel_ringbuffer *ringbuf,
 	struct intel_engine_cs *ring = ringbuf->ring;
 
 	intel_logical_ring_advance(ringbuf);
+	request->tail = ringbuf->tail;
 
 	if (intel_ring_stopped(ring))
 		return;
 
-	execlists_context_queue(ring, ctx, ringbuf->tail, request);
+	execlists_context_queue(ring, ctx, request);
 }
 
 static int logical_ring_wrap_buffer(struct intel_ringbuffer *ringbuf,
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 441adc8fa535..0b68ac5a7298 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2096,7 +2096,7 @@ static int ring_wait_for_space(struct intel_engine_cs *ring, int n)
 		return 0;
 
 	list_for_each_entry(request, &ring->request_list, list) {
-		space = __intel_ring_space(request->postfix, ringbuf->tail,
+		space = __intel_ring_space(request->tail, ringbuf->tail,
 					   ringbuf->size);
 		if (space >= n)
 			break;
-- 
2.1.4