USB: OHCI: add SG support
Apparently nobody ever remembered to add Scatter-Gather support to
ohci-hcd. This patch adds it.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ohci-q.c b/drivers/usb/host/ohci-q.c
index d4253e3..517d04d 100644
--- a/drivers/usb/host/ohci-q.c
+++ b/drivers/usb/host/ohci-q.c
@@ -602,6 +602,8 @@
u32 info = 0;
int is_out = usb_pipeout (urb->pipe);
int periodic = 0;
+ int i, this_sg_len, n;
+ struct scatterlist *sg;
/* OHCI handles the bulk/interrupt data toggles itself. We just
* use the device toggle bits for resetting, and rely on the fact
@@ -615,10 +617,24 @@
list_add (&urb_priv->pending, &ohci->pending);
- if (data_len)
- data = urb->transfer_dma;
- else
- data = 0;
+ i = urb->num_mapped_sgs;
+ if (data_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), data_len);
+ } else {
+ sg = NULL;
+ if (data_len)
+ data = urb->transfer_dma;
+ else
+ data = 0;
+ this_sg_len = data_len;
+ }
/* NOTE: TD_CC is set so we can tell which TDs the HC processed by
* using TD_CC_GET, as well as by seeing them on the done list.
@@ -639,17 +655,29 @@
? TD_T_TOGGLE | TD_CC | TD_DP_OUT
: TD_T_TOGGLE | TD_CC | TD_DP_IN;
/* TDs _could_ transfer up to 8K each */
- while (data_len > 4096) {
- td_fill (ohci, info, data, 4096, urb, cnt);
- data += 4096;
- data_len -= 4096;
+ for (;;) {
+ n = min(this_sg_len, 4096);
+
+ /* maybe avoid ED halt on final TD short read */
+ if (n >= data_len || (i == 1 && n >= this_sg_len)) {
+ if (!(urb->transfer_flags & URB_SHORT_NOT_OK))
+ info |= TD_R;
+ }
+ td_fill(ohci, info, data, n, urb, cnt);
+ this_sg_len -= n;
+ data_len -= n;
+ data += n;
cnt++;
+
+ if (this_sg_len <= 0) {
+ if (--i <= 0 || data_len <= 0)
+ break;
+ sg = sg_next(sg);
+ data = sg_dma_address(sg);
+ this_sg_len = min_t(int, sg_dma_len(sg),
+ data_len);
+ }
}
- /* maybe avoid ED halt on final TD short read */
- if (!(urb->transfer_flags & URB_SHORT_NOT_OK))
- info |= TD_R;
- td_fill (ohci, info, data, data_len, urb, cnt);
- cnt++;
if ((urb->transfer_flags & URB_ZERO_PACKET)
&& cnt < urb_priv->length) {
td_fill (ohci, info, 0, 0, urb, cnt);