This patch (as1300) adds native scatter-gather support to ehci-hcd.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
Index: usb-2.6/drivers/usb/host/ehci-q.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-q.c
+++ usb-2.6/drivers/usb/host/ehci-q.c
@@ -604,9 +604,11 @@ qh_urb_transaction (
) {
struct ehci_qtd *qtd, *qtd_prev;
dma_addr_t buf;
- int len, maxpacket;
+ int len, this_sg_len, maxpacket;
int is_input;
u32 token;
+ int i;
+ struct scatterlist *sg;
/*
* URBs map to sequences of QTDs: one logical transaction
@@ -647,7 +649,20 @@ qh_urb_transaction (
/*
* data transfer stage: buffer setup
*/
- buf = urb->transfer_dma;
+ i = urb->num_sgs;
+ if (len > 0 && i > 0) {
+ sg = urb->sg->sg;
+ buf = 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;
+ buf = urb->transfer_dma;
+ this_sg_len = len;
+ }
if (is_input)
token |= (1 /* "in" */ << 8);
@@ -663,7 +678,9 @@ qh_urb_transaction (
for (;;) {
int this_qtd_len;
- this_qtd_len = qtd_fill(ehci, qtd, buf, len, token, maxpacket);
+ this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
+ maxpacket);
+ this_sg_len -= this_qtd_len;
len -= this_qtd_len;
buf += this_qtd_len;
@@ -679,8 +696,13 @@ qh_urb_transaction (
if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
token ^= QTD_TOGGLE;
- if (likely (len <= 0))
- break;
+ if (likely(this_sg_len <= 0)) {
+ if (--i <= 0 || len <= 0)
+ break;
+ sg = sg_next(sg);
+ buf = sg_dma_address(sg);
+ this_sg_len = min_t(int, sg_dma_len(sg), len);
+ }
qtd_prev = qtd;
qtd = ehci_qtd_alloc (ehci, flags);
Index: usb-2.6/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-hcd.c
+++ usb-2.6/drivers/usb/host/ehci-hcd.c
@@ -604,6 +604,8 @@ static int ehci_init(struct usb_hcd *hcd
}
ehci->command = temp;
+ /* Accept arbitrarily long scatter-gather lists */
+ hcd->self.sg_tablesize = ~0;
return 0;
}
--
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