On Fri, 12 Mar 2010, Alan Stern wrote:
> Maybe we could have the scatter-gather library put pointers to the
> scatterlist elements in the URBs, and then for each URB have usbmon
> call dma_sync_sg() with nelems set to 1 (see
> Documentation/DMA-API.txt). I'm not sure whether this will work
> properly if the original scatter-gather list contained more than one
> element, but it probably will. I can ask.
Here's a patch. Oliver, does it fix your problem?
Alan Stern
Index: usb-2.6/drivers/usb/mon/usb_mon.h
===================================================================
--- usb-2.6.orig/drivers/usb/mon/usb_mon.h
+++ usb-2.6/drivers/usb/mon/usb_mon.h
@@ -72,4 +72,6 @@ extern const struct file_operations mon_
extern struct mon_bus mon_bus0; /* Only for redundant checks */
+extern void usb_sg_sync_for_cpu(struct urb *urb, int nelems);
+
#endif /* __USB_MON_H */
Index: usb-2.6/drivers/usb/mon/mon_bin.c
===================================================================
--- usb-2.6.orig/drivers/usb/mon/mon_bin.c
+++ usb-2.6/drivers/usb/mon/mon_bin.c
@@ -410,6 +410,7 @@ static unsigned int mon_bin_get_data(con
*flag = 'Z';
return length;
}
+ usb_sg_sync_for_cpu(urb, 1);
mon_copy_to_buff(rp, offset, urb->transfer_buffer, length);
length = 0;
@@ -421,6 +422,7 @@ static unsigned int mon_bin_get_data(con
}
/* Copy up to the first non-addressable segment */
+ usb_sg_sync_for_cpu(urb, urb->num_sgs);
for_each_sg(urb->sg->sg, sg, urb->num_sgs, i) {
if (length == 0 || PageHighMem(sg_page(sg)))
break;
Index: usb-2.6/drivers/usb/mon/mon_text.c
===================================================================
--- usb-2.6.orig/drivers/usb/mon/mon_text.c
+++ usb-2.6/drivers/usb/mon/mon_text.c
@@ -170,6 +170,7 @@ static inline char mon_text_get_data(str
src = sg_virt(sg);
}
+ usb_sg_sync_for_cpu(urb, 1);
memcpy(ep->data, src, len);
return 0;
}
Index: usb-2.6/drivers/usb/core/message.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/message.c
+++ usb-2.6/drivers/usb/core/message.c
@@ -467,6 +467,7 @@ int usb_sg_init(struct usb_sg_request *i
io->urbs[i]->transfer_buffer = NULL;
if (dma) {
+ io->urbs[i]->sg = (struct usb_sg_request *) sg;
io->urbs[i]->transfer_dma = sg_dma_address(sg);
len = sg_dma_len(sg);
} else {
@@ -643,6 +644,35 @@ void usb_sg_cancel(struct usb_sg_request
}
EXPORT_SYMBOL_GPL(usb_sg_cancel);
+/**
+ * usb_sg_sync_for_cpu -- give ownership of DMA buffers to the CPU
+ * @urb: URB whose buffers should be affected
+ * @nelems: number of sg elements to affect
+ *
+ * This allows the CPU to access @urb's sg transfer buffers after @urb
+ * has completed but before sg_clean() has unmapped the buffers for DMA.
+ * This is intended solely for use by usbmon.
+ */
+void usb_sg_sync_for_cpu(struct urb *urb, int nelems)
+{
+ enum dma_data_direction dir;
+ struct scatterlist *sg;
+
+ if (!(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
+ return; /* Either not sg or not DMA */
+
+ if (urb->num_sgs == 0) { /* HCD has no native sg support */
+ sg = (struct scatterlist *) urb->sg;
+ if (!sg)
+ return; /* Coherent mapping, not sg-mapped */
+ } else { /* HCD has native sg support */
+ sg = urb->sg->sg;
+ }
+ dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+ dma_sync_sg_for_cpu(urb->dev->bus->controller, sg, nelems, dir);
+}
+EXPORT_SYMBOL_GPL(usb_sg_sync_for_cpu);
+
/*-------------------------------------------------------------------*/
/**
--
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