When the address of a request was not aligned with an 8-byte boundary, the
USB DMA was unable to process it, necessitating the use of an internal
bounce buffer.
In these cases, the request->buf had to be copied to/from this bounce
buffer. However, if this unaligned address scenario arises, it is
unnecessary to perform heavy cache maintenance operations like
usb_gadget_map(unmap)_request_by_dev() on the request->buf, as the DMA
does not utilize it at all. it can be skipped at this case.
iperf3 tests on the rndis case:
Transmit speed (TX): Improved from 299Mbps to 440Mbps
Receive speed (RX): Improved from 290Mbps to 500Mbps
Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---
drivers/usb/cdns3/cdns3-gadget.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 1dcadef933e3..09a0882a4e97 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -800,7 +800,8 @@ void cdns3_gadget_giveback(struct cdns3_endpoint *priv_ep,
if (request->status == -EINPROGRESS)
request->status = status;
- usb_gadget_unmap_request_by_dev(priv_dev->sysdev, request,
+ if (likely(!(priv_req->flags & REQUEST_UNALIGNED)))
+ usb_gadget_unmap_request_by_dev(priv_dev->sysdev, request,
priv_ep->dir);
if ((priv_req->flags & REQUEST_UNALIGNED) &&
@@ -2543,10 +2544,12 @@ static int __cdns3_gadget_ep_queue(struct usb_ep *ep,
if (ret < 0)
return ret;
- ret = usb_gadget_map_request_by_dev(priv_dev->sysdev, request,
+ if (likely(!(priv_req->flags & REQUEST_UNALIGNED))) {
+ ret = usb_gadget_map_request_by_dev(priv_dev->sysdev, request,
usb_endpoint_dir_in(ep->desc));
- if (ret)
- return ret;
+ if (ret)
+ return ret;
+ }
list_add_tail(&request->list, &priv_ep->deferred_req_list);
--
2.34.1
