drm/vc4: Allocate binner bo when starting to use the V3D

The binner BO is not required until the V3D is in use, so avoid
allocating it at probe and do it on the first non-dumb BO allocation.

Keep track of which clients are using the V3D and liberate the buffer
when there is none left, using a kref. Protect the logic with a
mutex to avoid race conditions.

The binner BO is created at the time of the first render ioctl and is
destroyed when there is no client and no exec job using it left.

The Out-Of-Memory (OOM) interrupt also gets some tweaking, to avoid
enabling it before having allocated a binner bo.

We also want to keep the BO alive during runtime suspend/resume to avoid
failing to allocate it at resume. This happens when the CMA pool is
full at that point and results in a hard crash.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20190516145544.29051-5-paul.kocialkowski@bootlin.com

1 files changed, 49 insertions, 13 deletions

diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index c16db4665af6..0533646a4d13 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -294,6 +294,14 @@ static int bin_bo_alloc(struct vc4_dev *vc4)
 			WARN_ON_ONCE(sizeof(vc4->bin_alloc_used) * 8 !=
 				     bo->base.base.size / vc4->bin_alloc_size);
 
+			kref_init(&vc4->bin_bo_kref);
+
+			/* Enable the out-of-memory interrupt to set our
+			 * newly-allocated binner BO, potentially from an
+			 * already-pending-but-masked interrupt.
+			 */
+			V3D_WRITE(V3D_INTENA, V3D_INT_OUTOMEM);
+
 			break;
 		}
 
@@ -313,6 +321,47 @@ static int bin_bo_alloc(struct vc4_dev *vc4)
 	return ret;
 }
 
+int vc4_v3d_bin_bo_get(struct vc4_dev *vc4, bool *used)
+{
+	int ret = 0;
+
+	mutex_lock(&vc4->bin_bo_lock);
+
+	if (used && *used)
+		goto complete;
+
+	if (vc4->bin_bo)
+		kref_get(&vc4->bin_bo_kref);
+	else
+		ret = bin_bo_alloc(vc4);
+
+	if (ret == 0 && used)
+		*used = true;
+
+complete:
+	mutex_unlock(&vc4->bin_bo_lock);
+
+	return ret;
+}
+
+static void bin_bo_release(struct kref *ref)
+{
+	struct vc4_dev *vc4 = container_of(ref, struct vc4_dev, bin_bo_kref);
+
+	if (WARN_ON_ONCE(!vc4->bin_bo))
+		return;
+
+	drm_gem_object_put_unlocked(&vc4->bin_bo->base.base);
+	vc4->bin_bo = NULL;
+}
+
+void vc4_v3d_bin_bo_put(struct vc4_dev *vc4)
+{
+	mutex_lock(&vc4->bin_bo_lock);
+	kref_put(&vc4->bin_bo_kref, bin_bo_release);
+	mutex_unlock(&vc4->bin_bo_lock);
+}
+
 #ifdef CONFIG_PM
 static int vc4_v3d_runtime_suspend(struct device *dev)
 {
@@ -321,9 +370,6 @@ static int vc4_v3d_runtime_suspend(struct device *dev)
 
 	vc4_irq_uninstall(vc4->dev);
 
-	drm_gem_object_put_unlocked(&vc4->bin_bo->base.base);
-	vc4->bin_bo = NULL;
-
 	clk_disable_unprepare(v3d->clk);
 
 	return 0;
@@ -335,10 +381,6 @@ static int vc4_v3d_runtime_resume(struct device *dev)
 	struct vc4_dev *vc4 = v3d->vc4;
 	int ret;
 
-	ret = bin_bo_alloc(vc4);
-	if (ret)
-		return ret;
-
 	ret = clk_prepare_enable(v3d->clk);
 	if (ret != 0)
 		return ret;
@@ -405,12 +447,6 @@ static int vc4_v3d_bind(struct device *dev, struct device *master, void *data)
 	if (ret != 0)
 		return ret;
 
-	ret = bin_bo_alloc(vc4);
-	if (ret) {
-		clk_disable_unprepare(v3d->clk);
-		return ret;
-	}
-
 	/* Reset the binner overflow address/size at setup, to be sure
 	 * we don't reuse an old one.
 	 */