linux 2.6.16.38 w/ vs2.0.3-rc1

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

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 2ffb0d6..1af0f2d 100644 (file)
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -33,9 +33,7 @@ pci_alloc_consistent(struct pci_dev *dev, size_t size,
 
 Consistent memory is memory for which a write by either the device or
 the processor can immediately be read by the processor or device
-without having to worry about caching effects.  (You may however need
-to make sure to flush the processor's write buffers before telling
-devices to read that memory.)
+without having to worry about caching effects.
 
 This routine allocates a region of <size> bytes of consistent memory.
 it also returns a <dma_handle> which may be cast to an unsigned
@@ -306,12 +304,12 @@ dma address with dma_mapping_error(). A non zero return value means the mapping
 could not be created and the driver should take appropriate action (eg
 reduce current DMA mapping usage or delay and try again later).
 
-       int
-       dma_map_sg(struct device *dev, struct scatterlist *sg,
-               int nents, enum dma_data_direction direction)
-       int
-       pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg,
-               int nents, int direction)
+int
+dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
+          enum dma_data_direction direction)
+int
+pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg,
+          int nents, int direction)
 
 Maps a scatter gather list from the block layer.
 
@@ -329,33 +327,12 @@ critical that the driver do something, in the case of a block driver
 aborting the request or even oopsing is better than doing nothing and
 corrupting the filesystem.
 
-With scatterlists, you use the resulting mapping like this:
-
-       int i, count = dma_map_sg(dev, sglist, nents, direction);
-       struct scatterlist *sg;
-
-       for (i = 0, sg = sglist; i < count; i++, sg++) {
-               hw_address[i] = sg_dma_address(sg);
-               hw_len[i] = sg_dma_len(sg);
-       }
-
-where nents is the number of entries in the sglist.
-
-The implementation is free to merge several consecutive sglist entries
-into one (e.g. with an IOMMU, or if several pages just happen to be
-physically contiguous) and returns the actual number of sg entries it
-mapped them to. On failure 0, is returned.
-
-Then you should loop count times (note: this can be less than nents times)
-and use sg_dma_address() and sg_dma_len() macros where you previously
-accessed sg->address and sg->length as shown above.
-
-       void
-       dma_unmap_sg(struct device *dev, struct scatterlist *sg,
-               int nhwentries, enum dma_data_direction direction)
-       void
-       pci_unmap_sg(struct pci_dev *hwdev, struct scatterlist *sg,
-               int nents, int direction)
+void
+dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nhwentries,
+            enum dma_data_direction direction)
+void
+pci_unmap_sg(struct pci_dev *hwdev, struct scatterlist *sg,
+            int nents, int direction)
 
 unmap the previously mapped scatter/gather list.  All the parameters
 must be the same as those and passed in to the scatter/gather mapping