[SCSI] bsg: fix oops on remove

[linux-2.6-omap-h63xx.git] / Documentation / DMA-API.txt

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index cc7a8c39fb6fbf224483355cd169a2cee0d6a30a..80d150458c80c5ac7f7f5f75b3e6ff8a602a19ca 100644 (file)
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -68,6 +68,9 @@ size and dma_handle must all be the same as those passed into the
 consistent allocate.  cpu_addr must be the virtual address returned by
 the consistent allocate.
 
 consistent allocate.  cpu_addr must be the virtual address returned by
 the consistent allocate.
 

+Note that unlike their sibling allocation calls, these routines
+may only be called with IRQs enabled.
+

 
 Part Ib - Using small dma-coherent buffers
 ------------------------------------------
 
 Part Ib - Using small dma-coherent buffers
 ------------------------------------------


@@ -142,7 +145,7 @@ Part Ic - DMA addressing limitations
 int
 dma_supported(struct device *dev, u64 mask)
 int
 int
 dma_supported(struct device *dev, u64 mask)
 int

-pci_dma_supported(struct device *dev, u64 mask)
+pci_dma_supported(struct pci_dev *hwdev, u64 mask)

 
 Checks to see if the device can support DMA to the memory described by
 mask.
 
 Checks to see if the device can support DMA to the memory described by
 mask.


@@ -186,7 +189,7 @@ dma_addr_t
 dma_map_single(struct device *dev, void *cpu_addr, size_t size,
                      enum dma_data_direction direction)
 dma_addr_t
 dma_map_single(struct device *dev, void *cpu_addr, size_t size,
                      enum dma_data_direction direction)
 dma_addr_t

-pci_map_single(struct device *dev, void *cpu_addr, size_t size,
+pci_map_single(struct pci_dev *hwdev, void *cpu_addr, size_t size,

                      int direction)
 
 Maps a piece of processor virtual memory so it can be accessed by the
                      int direction)
 
 Maps a piece of processor virtual memory so it can be accessed by the


@@ -392,6 +395,71 @@ Notes:  You must do this:
 
 See also dma_map_single().
 
 
 See also dma_map_single().
 

+dma_addr_t
+dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size,
+                    enum dma_data_direction dir,
+                    struct dma_attrs *attrs)
+
+void
+dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
+                      size_t size, enum dma_data_direction dir,
+                      struct dma_attrs *attrs)
+
+int
+dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
+                int nents, enum dma_data_direction dir,
+                struct dma_attrs *attrs)
+
+void
+dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl,
+                  int nents, enum dma_data_direction dir,
+                  struct dma_attrs *attrs)
+
+The four functions above are just like the counterpart functions
+without the _attrs suffixes, except that they pass an optional
+struct dma_attrs*.
+
+struct dma_attrs encapsulates a set of "dma attributes". For the
+definition of struct dma_attrs see linux/dma-attrs.h.
+
+The interpretation of dma attributes is architecture-specific, and
+each attribute should be documented in Documentation/DMA-attributes.txt.
+
+If struct dma_attrs* is NULL, the semantics of each of these
+functions is identical to those of the corresponding function
+without the _attrs suffix. As a result dma_map_single_attrs()
+can generally replace dma_map_single(), etc.
+
+As an example of the use of the *_attrs functions, here's how
+you could pass an attribute DMA_ATTR_FOO when mapping memory
+for DMA:
+
+#include <linux/dma-attrs.h>
+/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and
+ * documented in Documentation/DMA-attributes.txt */
+...
+
+       DEFINE_DMA_ATTRS(attrs);
+       dma_set_attr(DMA_ATTR_FOO, &attrs);
+       ....
+       n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr);
+       ....
+
+Architectures that care about DMA_ATTR_FOO would check for its
+presence in their implementations of the mapping and unmapping
+routines, e.g.:
+
+void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr,
+                            size_t size, enum dma_data_direction dir,
+                            struct dma_attrs *attrs)
+{
+       ....
+       int foo =  dma_get_attr(DMA_ATTR_FOO, attrs);
+       ....
+       if (foo)
+               /* twizzle the frobnozzle */
+       ....
+

 
 Part II - Advanced dma_ usage
 -----------------------------
 
 Part II - Advanced dma_ usage
 -----------------------------