If the hardware (like DMA engine) could support large usb request exceeds
maximum packet size, use larger buffer when performing Rx/Tx could reduce
request numbers and improve performance.

Signed-off-by: Macpaul Lin <macpaul....@mediatek.com>
---
 drivers/usb/gadget/function/u_serial.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/u_serial.c 
b/drivers/usb/gadget/function/u_serial.c
index 3cfc6e2..cdcc070 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -80,6 +80,8 @@
 #define QUEUE_SIZE             16
 #define WRITE_BUF_SIZE         8192            /* TX only */
 #define GS_CONSOLE_BUF_SIZE    8192
+/* for hardware can do more than max packet */
+#define REQ_BUF_SIZE           4096
 
 /* console info */
 struct gs_console {
@@ -247,7 +249,8 @@ static int gs_start_tx(struct gs_port *port)
                        break;
 
                req = list_entry(pool->next, struct usb_request, list);
-               len = gs_send_packet(port, req->buf, in->maxpacket);
+               len = gs_send_packet(port, req->buf, in->can_exceed_maxp ?
+                               REQ_BUF_SIZE : in->maxpacket);
                if (len == 0) {
                        wake_up_interruptible(&port->drain_wait);
                        break;
@@ -514,7 +517,9 @@ static int gs_alloc_requests(struct usb_ep *ep, struct 
list_head *head,
         * be as speedy as we might otherwise be.
         */
        for (i = 0; i < n; i++) {
-               req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
+               req = gs_alloc_req(ep, ep->can_exceed_maxp ?
+                                       REQ_BUF_SIZE : ep->maxpacket,
+                                       GFP_ATOMIC);
                if (!req)
                        return list_empty(head) ? -ENOMEM : 0;
                req->complete = fn;
-- 
1.7.9.5

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