ioat: switch watchdog and reset handler from workqueue to timer

In order to support dynamic resizing of the descriptor ring or polling
for a descriptor in the presence of a hung channel the reset handler
needs to make progress while in a non-preemptible context.  The current
workqueue implementation precludes polling channel reset completion
under spin_lock().

This conversion also allows us to return to opportunistic cleanup in the
ioat2 case as the timer implementation guarantees at least one cleanup
after every descriptor is submitted.  This means the worst case
completion latency becomes the timer frequency (for exceptional
circumstances), but with the benefit of avoiding busy waiting when the
lock is contended.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/dma/ioat/dma_v2.h b/drivers/dma/ioat/dma_v2.h
index bdde5373cf66..73b04a2eb4b0 100644
--- a/drivers/dma/ioat/dma_v2.h
+++ b/drivers/dma/ioat/dma_v2.h
@@ -127,6 +127,16 @@ ioat2_get_ring_ent(struct ioat2_dma_chan *ioat, u16 idx)
         return ioat->ring[idx & ioat2_ring_mask(ioat)];
 }
 
+static inline void ioat2_set_chainaddr(struct ioat2_dma_chan *ioat, u64 addr)
+{
+        struct ioat_chan_common *chan = &ioat->base;
+
+        writel(addr & 0x00000000FFFFFFFF,
+               chan->reg_base + IOAT2_CHAINADDR_OFFSET_LOW);
+        writel(addr >> 32,
+               chan->reg_base + IOAT2_CHAINADDR_OFFSET_HIGH);
+}
+
 int __devinit ioat2_dma_probe(struct ioatdma_device *dev, int dca);
 int __devinit ioat3_dma_probe(struct ioatdma_device *dev, int dca);
 struct dca_provider * __devinit ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase);