tree-wide: fix assorted typos all over the place

[linux-block.git] / drivers / usb / core / message.c

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 9720e699f4729737cbdd90946f234e567fc0d874..e80f1af438c8f2af202438685662495ebc5df307 100644 (file)
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -459,35 +459,23 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
                        io->urbs[i]->context = io;
 
                        /*
-                        * Some systems need to revert to PIO when DMA is
-                        * temporarily unavailable.  For their sakes, both
-                        * transfer_buffer and transfer_dma are set when
-                        * possible.  However this can only work on systems
-                        * without:
+                        * Some systems need to revert to PIO when DMA is temporarily
+                        * unavailable.  For their sakes, both transfer_buffer and
+                        * transfer_dma are set when possible.
                         *
-                        *  - HIGHMEM, since DMA buffers located in high memory
-                        *    are not directly addressable by the CPU for PIO;
-                        *
-                        *  - IOMMU, since dma_map_sg() is allowed to use an
-                        *    IOMMU to make virtually discontiguous buffers be
-                        *    "dma-contiguous" so that PIO and DMA need diferent
-                        *    numbers of URBs.
-                        *
-                        * So when HIGHMEM or IOMMU are in use, transfer_buffer
-                        * is NULL to prevent stale pointers and to help spot
-                        * bugs.
+                        * Note that if IOMMU coalescing occurred, we cannot
+                        * trust sg_page anymore, so check if S/G list shrunk.
                         */
+                       if (io->nents == io->entries && !PageHighMem(sg_page(sg)))
+                               io->urbs[i]->transfer_buffer = sg_virt(sg);
+                       else
+                               io->urbs[i]->transfer_buffer = NULL;
+
                        if (dma) {
                                io->urbs[i]->transfer_dma = sg_dma_address(sg);
                                len = sg_dma_len(sg);
-#if defined(CONFIG_HIGHMEM) || defined(CONFIG_GART_IOMMU)
-                               io->urbs[i]->transfer_buffer = NULL;
-#else
-                               io->urbs[i]->transfer_buffer = sg_virt(sg);
-#endif
                        } else {
                                /* hc may use _only_ transfer_buffer */
-                               io->urbs[i]->transfer_buffer = sg_virt(sg);
                                len = sg->length;
                        }
 
@@ -1902,7 +1890,7 @@ static void cancel_async_set_config(struct usb_device *udev)
  * routine gets around the normal restrictions by using a work thread to
  * submit the change-config request.
  *
- * Returns 0 if the request was succesfully queued, error code otherwise.
+ * Returns 0 if the request was successfully queued, error code otherwise.
  * The caller has no way to know whether the queued request will eventually
  * succeed.
  */