3 files changed, 52 insertions, 3 deletions

diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
index a371b07a0981..f70cc74032ea 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -644,9 +644,13 @@ static void __cleanup(struct ioatdma_chan *ioat_chan, dma_addr_t phys_complete)
 		mod_timer(&ioat_chan->timer, jiffies + IDLE_TIMEOUT);
 	}
 
-	/* 5 microsecond delay per pending descriptor */
-	writew(min((5 * (active - i)), IOAT_INTRDELAY_MASK),
-	       ioat_chan->ioat_dma->reg_base + IOAT_INTRDELAY_OFFSET);
+	/* microsecond delay by sysfs variable  per pending descriptor */
+	if (ioat_chan->intr_coalesce != ioat_chan->prev_intr_coalesce) {
+		writew(min((ioat_chan->intr_coalesce * (active - i)),
+		       IOAT_INTRDELAY_MASK),
+		       ioat_chan->ioat_dma->reg_base + IOAT_INTRDELAY_OFFSET);
+		ioat_chan->prev_intr_coalesce = ioat_chan->intr_coalesce;
+	}
 }
 
 static void ioat_cleanup(struct ioatdma_chan *ioat_chan)
diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
index a9bc1a15b0d1..56200eefcf5e 100644
--- a/drivers/dma/ioat/dma.h
+++ b/drivers/dma/ioat/dma.h
@@ -142,11 +142,14 @@ struct ioatdma_chan {
 	spinlock_t prep_lock;
 	struct ioat_descs descs[2];
 	int desc_chunks;
+	int intr_coalesce;
+	int prev_intr_coalesce;
 };
 
 struct ioat_sysfs_entry {
 	struct attribute attr;
 	ssize_t (*show)(struct dma_chan *, char *);
+	ssize_t (*store)(struct dma_chan *, const char *, size_t);
 };
 
 /**
diff --git a/drivers/dma/ioat/sysfs.c b/drivers/dma/ioat/sysfs.c
index cb4a857ee21b..3ac677f29e8f 100644
--- a/drivers/dma/ioat/sysfs.c
+++ b/drivers/dma/ioat/sysfs.c
@@ -64,8 +64,24 @@ ioat_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 	return entry->show(&ioat_chan->dma_chan, page);
 }
 
+static ssize_t
+ioat_attr_store(struct kobject *kobj, struct attribute *attr,
+const char *page, size_t count)
+{
+	struct ioat_sysfs_entry *entry;
+	struct ioatdma_chan *ioat_chan;
+
+	entry = container_of(attr, struct ioat_sysfs_entry, attr);
+	ioat_chan = container_of(kobj, struct ioatdma_chan, kobj);
+
+	if (!entry->store)
+		return -EIO;
+	return entry->store(&ioat_chan->dma_chan, page, count);
+}
+
 const struct sysfs_ops ioat_sysfs_ops = {
 	.show	= ioat_attr_show,
+	.store  = ioat_attr_store,
 };
 
 void ioat_kobject_add(struct ioatdma_device *ioat_dma, struct kobj_type *type)
@@ -121,11 +137,37 @@ static ssize_t ring_active_show(struct dma_chan *c, char *page)
 }
 static struct ioat_sysfs_entry ring_active_attr = __ATTR_RO(ring_active);
 
+static ssize_t intr_coalesce_show(struct dma_chan *c, char *page)
+{
+	struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
+
+	return sprintf(page, "%d\n", ioat_chan->intr_coalesce);
+}
+
+static ssize_t intr_coalesce_store(struct dma_chan *c, const char *page,
+size_t count)
+{
+	int intr_coalesce = 0;
+	struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
+
+	if (sscanf(page, "%du", &intr_coalesce) != -1) {
+		if ((intr_coalesce < 0) ||
+		    (intr_coalesce > IOAT_INTRDELAY_MASK))
+			return -EINVAL;
+		ioat_chan->intr_coalesce = intr_coalesce;
+	}
+
+	return count;
+}
+
+static struct ioat_sysfs_entry intr_coalesce_attr = __ATTR_RW(intr_coalesce);
+
 static struct attribute *ioat_attrs[] = {
 	&ring_size_attr.attr,
 	&ring_active_attr.attr,
 	&ioat_cap_attr.attr,
 	&ioat_version_attr.attr,
+	&intr_coalesce_attr.attr,
 	NULL,
 };