drm/i915: Propagate errors from writing to ringbuffer

Preparing the ringbuffer for adding new commands can fail (a timeout
whilst waiting for the GPU to catch up and free some space). So check
for any potential error before overwriting HEAD with new commands, and
propagate that error back to the user where possible.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 61 insertions, 58 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 8a171394a9cf..02daf4e5c8e6 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -263,7 +263,7 @@ static int i915_dma_init(struct drm_device *dev, void *data,
  * instruction detected will be given a size of zero, which is a
  * signal to abort the rest of the buffer.
  */
-static int do_validate_cmd(int cmd)
+static int validate_cmd(int cmd)
 {
 	switch (((cmd >> 29) & 0x7)) {
 	case 0x0:
@@ -321,40 +321,27 @@ static int do_validate_cmd(int cmd)
 	return 0;
 }
 
-static int validate_cmd(int cmd)
-{
-	int ret = do_validate_cmd(cmd);
-
-/*	printk("validate_cmd( %x ): %d\n", cmd, ret); */
-
-	return ret;
-}
-
 static int i915_emit_cmds(struct drm_device * dev, int *buffer, int dwords)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	int i;
+	int i, ret;
 
 	if ((dwords+1) * sizeof(int) >= dev_priv->render_ring.size - 8)
 		return -EINVAL;
 
-	BEGIN_LP_RING((dwords+1)&~1);
-
 	for (i = 0; i < dwords;) {
-		int cmd, sz;
-
-		cmd = buffer[i];
-
-		if ((sz = validate_cmd(cmd)) == 0 || i + sz > dwords)
+		int sz = validate_cmd(buffer[i]);
+		if (sz == 0 || i + sz > dwords)
 			return -EINVAL;
-
-		OUT_RING(cmd);
-
-		while (++i, --sz) {
-			OUT_RING(buffer[i]);
-		}
+		i += sz;
 	}
 
+	ret = BEGIN_LP_RING((dwords+1)&~1);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < dwords; i++)
+		OUT_RING(buffer[i]);
 	if (dwords & 1)
 		OUT_RING(0);
 
@@ -368,7 +355,9 @@ i915_emit_box(struct drm_device *dev,
 	      struct drm_clip_rect *boxes,
 	      int i, int DR1, int DR4)
 {
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_clip_rect box = boxes[i];
+	int ret;
 
 	if (box.y2 <= box.y1 || box.x2 <= box.x1 || box.y2 <= 0 || box.x2 <= 0) {
 		DRM_ERROR("Bad box %d,%d..%d,%d\n",
@@ -377,22 +366,27 @@ i915_emit_box(struct drm_device *dev,
 	}
 
 	if (INTEL_INFO(dev)->gen >= 4) {
-		BEGIN_LP_RING(4);
+		ret = BEGIN_LP_RING(4);
+		if (ret)
+			return ret;
+
 		OUT_RING(GFX_OP_DRAWRECT_INFO_I965);
 		OUT_RING((box.x1 & 0xffff) | (box.y1 << 16));
 		OUT_RING(((box.x2 - 1) & 0xffff) | ((box.y2 - 1) << 16));
 		OUT_RING(DR4);
-		ADVANCE_LP_RING();
 	} else {
-		BEGIN_LP_RING(6);
+		ret = BEGIN_LP_RING(6);
+		if (ret)
+			return ret;
+
 		OUT_RING(GFX_OP_DRAWRECT_INFO);
 		OUT_RING(DR1);
 		OUT_RING((box.x1 & 0xffff) | (box.y1 << 16));
 		OUT_RING(((box.x2 - 1) & 0xffff) | ((box.y2 - 1) << 16));
 		OUT_RING(DR4);
 		OUT_RING(0);
-		ADVANCE_LP_RING();
 	}
+	ADVANCE_LP_RING();
 
 	return 0;
 }
@@ -412,12 +406,13 @@ static void i915_emit_breadcrumb(struct drm_device *dev)
 	if (master_priv->sarea_priv)
 		master_priv->sarea_priv->last_enqueue = dev_priv->counter;
 
-	BEGIN_LP_RING(4);
-	OUT_RING(MI_STORE_DWORD_INDEX);
-	OUT_RING(I915_BREADCRUMB_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
-	OUT_RING(dev_priv->counter);
-	OUT_RING(0);
-	ADVANCE_LP_RING();
+	if (BEGIN_LP_RING(4) == 0) {
+		OUT_RING(MI_STORE_DWORD_INDEX);
+		OUT_RING(I915_BREADCRUMB_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
+		OUT_RING(dev_priv->counter);
+		OUT_RING(0);
+		ADVANCE_LP_RING();
+	}
 }
 
 static int i915_dispatch_cmdbuffer(struct drm_device * dev,
@@ -458,8 +453,9 @@ static int i915_dispatch_batchbuffer(struct drm_device * dev,
 				     drm_i915_batchbuffer_t * batch,
 				     struct drm_clip_rect *cliprects)
 {
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	int nbox = batch->num_cliprects;
-	int i = 0, count;
+	int i, count, ret;
 
 	if ((batch->start | batch->used) & 0x7) {
 		DRM_ERROR("alignment");
@@ -469,17 +465,19 @@ static int i915_dispatch_batchbuffer(struct drm_device * dev,
 	i915_kernel_lost_context(dev);
 
 	count = nbox ? nbox : 1;
-
 	for (i = 0; i < count; i++) {
 		if (i < nbox) {
-			int ret = i915_emit_box(dev, cliprects, i,
-						batch->DR1, batch->DR4);
+			ret = i915_emit_box(dev, cliprects, i,
+					    batch->DR1, batch->DR4);
 			if (ret)
 				return ret;
 		}
 
 		if (!IS_I830(dev) && !IS_845G(dev)) {
-			BEGIN_LP_RING(2);
+			ret = BEGIN_LP_RING(2);
+			if (ret)
+				return ret;
+
 			if (INTEL_INFO(dev)->gen >= 4) {
 				OUT_RING(MI_BATCH_BUFFER_START | (2 << 6) | MI_BATCH_NON_SECURE_I965);
 				OUT_RING(batch->start);
@@ -487,26 +485,29 @@ static int i915_dispatch_batchbuffer(struct drm_device * dev,
 				OUT_RING(MI_BATCH_BUFFER_START | (2 << 6));
 				OUT_RING(batch->start | MI_BATCH_NON_SECURE);
 			}
-			ADVANCE_LP_RING();
 		} else {
-			BEGIN_LP_RING(4);
+			ret = BEGIN_LP_RING(4);
+			if (ret)
+				return ret;
+
 			OUT_RING(MI_BATCH_BUFFER);
 			OUT_RING(batch->start | MI_BATCH_NON_SECURE);
 			OUT_RING(batch->start + batch->used - 4);
 			OUT_RING(0);
-			ADVANCE_LP_RING();
 		}
+		ADVANCE_LP_RING();
 	}
 
 
 	if (IS_G4X(dev) || IS_GEN5(dev)) {
-		BEGIN_LP_RING(2);
-		OUT_RING(MI_FLUSH | MI_NO_WRITE_FLUSH | MI_INVALIDATE_ISP);
-		OUT_RING(MI_NOOP);
-		ADVANCE_LP_RING();
+		if (BEGIN_LP_RING(2) == 0) {
+			OUT_RING(MI_FLUSH | MI_NO_WRITE_FLUSH | MI_INVALIDATE_ISP);
+			OUT_RING(MI_NOOP);
+			ADVANCE_LP_RING();
+		}
 	}
-	i915_emit_breadcrumb(dev);
 
+	i915_emit_breadcrumb(dev);
 	return 0;
 }
 
@@ -515,6 +516,7 @@ static int i915_dispatch_flip(struct drm_device * dev)
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	struct drm_i915_master_private *master_priv =
 		dev->primary->master->driver_priv;
+	int ret;
 
 	if (!master_priv->sarea_priv)
 		return -EINVAL;
@@ -526,12 +528,13 @@ static int i915_dispatch_flip(struct drm_device * dev)
 
 	i915_kernel_lost_context(dev);
 
-	BEGIN_LP_RING(2);
+	ret = BEGIN_LP_RING(10);
+	if (ret)
+		return ret;
+
 	OUT_RING(MI_FLUSH | MI_READ_FLUSH);
 	OUT_RING(0);
-	ADVANCE_LP_RING();
 
-	BEGIN_LP_RING(6);
 	OUT_RING(CMD_OP_DISPLAYBUFFER_INFO | ASYNC_FLIP);
 	OUT_RING(0);
 	if (dev_priv->current_page == 0) {
@@ -542,21 +545,21 @@ static int i915_dispatch_flip(struct drm_device * dev)
 		dev_priv->current_page = 0;
 	}
 	OUT_RING(0);
-	ADVANCE_LP_RING();
 
-	BEGIN_LP_RING(2);
 	OUT_RING(MI_WAIT_FOR_EVENT | MI_WAIT_FOR_PLANE_A_FLIP);
 	OUT_RING(0);
+
 	ADVANCE_LP_RING();
 
 	master_priv->sarea_priv->last_enqueue = dev_priv->counter++;
 
-	BEGIN_LP_RING(4);
-	OUT_RING(MI_STORE_DWORD_INDEX);
-	OUT_RING(I915_BREADCRUMB_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
-	OUT_RING(dev_priv->counter);
-	OUT_RING(0);
-	ADVANCE_LP_RING();
+	if (BEGIN_LP_RING(4) == 0) {
+		OUT_RING(MI_STORE_DWORD_INDEX);
+		OUT_RING(I915_BREADCRUMB_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
+		OUT_RING(dev_priv->counter);
+		OUT_RING(0);
+		ADVANCE_LP_RING();
+	}
 
 	master_priv->sarea_priv->pf_current_page = dev_priv->current_page;
 	return 0;