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path: root/drivers/usb/core/usb.c
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Diffstat (limited to 'drivers/usb/core/usb.c')
-rw-r--r--drivers/usb/core/usb.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 12918839c2f1..137f930dea58 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -253,6 +253,7 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
dev->dev.bus = &usb_bus_type;
dev->dev.type = &usb_device_type;
dev->dev.dma_mask = bus->controller->dma_mask;
+ set_dev_node(&dev->dev, dev_to_node(bus->controller));
dev->state = USB_STATE_ATTACHED;
INIT_LIST_HEAD(&dev->ep0.urb_list);
@@ -578,11 +579,12 @@ int __usb_get_extra_descriptor(char *buffer, unsigned size,
* address (through the pointer provided).
*
* These buffers are used with URB_NO_xxx_DMA_MAP set in urb->transfer_flags
- * to avoid behaviors like using "DMA bounce buffers", or tying down I/O
- * mapping hardware for long idle periods. The implementation varies between
+ * to avoid behaviors like using "DMA bounce buffers", or thrashing IOMMU
+ * hardware during URB completion/resubmit. The implementation varies between
* platforms, depending on details of how DMA will work to this device.
- * Using these buffers also helps prevent cacheline sharing problems on
- * architectures where CPU caches are not DMA-coherent.
+ * Using these buffers also eliminates cacheline sharing problems on
+ * architectures where CPU caches are not DMA-coherent. On systems without
+ * bus-snooping caches, these buffers are uncached.
*
* When the buffer is no longer used, free it with usb_buffer_free().
*/
@@ -607,7 +609,7 @@ void *usb_buffer_alloc(
*
* This reclaims an I/O buffer, letting it be reused. The memory must have
* been allocated using usb_buffer_alloc(), and the parameters must match
- * those provided in that allocation request.
+ * those provided in that allocation request.
*/
void usb_buffer_free(
struct usb_device *dev,