Re: [PATCH 4/5] dma-mapping: add a dma_ops_bypass flag to struct device

Several IOMMU drivers have a bypass mode where they can use a direct
mapping if the devices DMA mask is large enough.  Add generic support
to the core dma-mapping code to do that to switch those drivers to
a common solution.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/device.h |  8 +++++
 kernel/dma/Kconfig     |  8 +++++
 kernel/dma/mapping.c   | 74 +++++++++++++++++++++++++++++-------------
 3 files changed, 68 insertions(+), 22 deletions(-)

diff --git a/include/linux/device.h b/include/linux/device.h
index 4c4af98321ebd6..1f71acf37f78d7 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h

@@ -523,6 +523,11 @@ struct dev_links_info {
  *		  sync_state() callback.
  * @dma_coherent: this particular device is dma coherent, even if the
  *		architecture supports non-coherent devices.
+ * @dma_ops_bypass: If set to %true then the dma_ops are bypassed for the
+ *		streaming DMA operations (->map_* / ->unmap_* / ->sync_*),
+ *		and optionall (if the coherent mask is large enough) also