[lkml]   [2003]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
SubjectHandling of bounce buffers by rh_call_control
The following patch

===== drivers/usb/hcd.c 1.10 vs edited =====
--- 1.10/drivers/usb/hcd.c Mon Mar 31 14:22:42 2003
+++ edited/drivers/usb/hcd.c Wed Dec 17 11:26:53 2003
@@ -323,7 +323,7 @@
struct usb_ctrlrequest *cmd = (struct usb_ctrlrequest *) urb->setup_packet;
u16 typeReq, wValue, wIndex, wLength;
const u8 *bufp = 0;
- u8 *ubuf = urb->transfer_buffer;
+ u8 *ubuf = (u8 *) urb->transfer_dma;
int len = 0;

typeReq = (cmd->bRequestType << 8) | cmd->bRequest;
seems to be needed to make the following code later in the function work

if (bufp) {
if (urb->transfer_buffer_length < len)
len = urb->transfer_buffer_length;
urb->actual_length = len;
// always USB_DIR_IN, toward host
memcpy (ubuf, bufp, len);
in the case where bounce buffers are being used to implement PCI DMA
operations. Without the patch, the subsequent pci_unmap_single copies
the contents of the bounce buffer over the top of urb->transfer_buffer,
destroying what the memcpy() put there.

My USB knowledge is pretty limited, so I've no idea whether this patch
adversely affects anything else in rh_call_control.

The patch is against 2.4.23-pre-something, but I see the code's the same
in 2.6.

Richard \\\ SH-4/SH-5 Core & Debug Architect
Curnow \\\ SuperH (UK) Ltd, Bristol
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:59    [W:0.071 / U:0.232 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site