From: Ming Lei <tom.leiming@xxxxxxxxx>
This patch adds native scatter-gather support to uhci-hcd.
Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
v1: some trivial fix on Alan's comment.
---
drivers/usb/host/uhci-q.c | 33 +++++++++++++++++++++++++++++----
1 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index d3ade40..51031c2 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -917,10 +917,13 @@ static int uhci_submit_common(struct uhci_hcd *uhci, struct urb *urb,
unsigned long destination, status;
int maxsze = le16_to_cpu(qh->hep->desc.wMaxPacketSize);
int len = urb->transfer_buffer_length;
- dma_addr_t data = urb->transfer_dma;
+ int this_sg_len;
+ dma_addr_t data;
__le32 *plink;
struct urb_priv *urbp = urb->hcpriv;
unsigned int toggle;
+ struct scatterlist *sg;
+ int i;
if (len < 0)
return -EINVAL;
@@ -937,12 +940,26 @@ static int uhci_submit_common(struct uhci_hcd *uhci, struct urb *urb,
if (usb_pipein(urb->pipe))
status |= TD_CTRL_SPD;
+ i = urb->num_sgs;
+ if (len > 0 && i > 0) {
+ sg = urb->sg;
+ data = sg_dma_address(sg);
+
+ /* urb->transfer_buffer_length may be smaller than the
+ * size of the scatterlist (or vice versa)
+ */
+ this_sg_len = min_t(int, sg_dma_len(sg), len);
+ } else {
+ sg = NULL;
+ data = urb->transfer_dma;
+ this_sg_len = len;
+ }
/*
* Build the DATA TDs
*/
plink = NULL;
td = qh->dummy_td;
- do { /* Allow zero length packets */
+ for (;;) { /* Allow zero length packets */
int pktsze = maxsze;
if (len <= pktsze) { /* The last packet */
@@ -965,10 +982,18 @@ static int uhci_submit_common(struct uhci_hcd *uhci, struct urb *urb,
plink = &td->link;
status |= TD_CTRL_ACTIVE;
+ toggle ^= 1;
data += pktsze;
+ this_sg_len -= pktsze;
len -= maxsze;
- toggle ^= 1;
- } while (len > 0);
+ if (this_sg_len <= 0) {
+ if (--i <= 0 || len <= 0)
+ break;
+ sg = sg_next(sg);
+ data = sg_dma_address(sg);
+ this_sg_len = min_t(int, sg_dma_len(sg), len);
+ }
+ }
/*
* URB_ZERO_PACKET means adding a 0-length packet, if direction
--
1.7.3
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