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authorAlan Stern <stern@rowland.harvard.edu>2009-11-06 12:29:40 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2009-12-11 11:55:19 -0800
commit40f8db8f8f5af2cafeb976ae15e11aca641a931d (patch)
treeb2da27baeab34919264b60f7679cfef62daa933d /drivers/usb/host/ehci-q.c
parent3a2b808e95287c8235e25a833fda3dad3e9853ef (diff)
USB: EHCI: add native scatter-gather support
This patch (as1300) adds native scatter-gather support to ehci-hcd. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/host/ehci-q.c')
-rw-r--r--drivers/usb/host/ehci-q.c32
1 files changed, 27 insertions, 5 deletions
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 139a2cc3f641..a427d3b00634 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -616,9 +616,11 @@ 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
@@ -659,7 +661,20 @@ 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);
@@ -675,7 +690,9 @@ 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;
@@ -691,8 +708,13 @@ 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);