[PATCH] USB: g_file_storage: fix handling zero-length packet

[sangsu <sangsu@gmail.com>]

According to "CH 5.5.3. Control Transfer Packet Size Constraints",
Zero-length packet should be sent when the last data payload size
is equal to the endpoint's MaxPacketSize. This patch helps
g_file_storage send zero-length packet properly.

This is tested in s3c2440/s5c7329 architectures and works well.

Signed-off-by: SangSu Park<sangsu@gmail.com>
---
driver/usb/gadget/file_storage.c | 3++-
1 files changed, 2 insertion(+), 1 deletions(-)

--- a/drivers/usb/gadget/file_storage.c	2008-09-01 11:13:03.000000000 -0400
+++ b/drivers/usb/gadget/file_storage.c	2008-09-01 11:16:41.000000000 -0400
@@ -1463,7 +1463,8 @@
	if (rc >= 0 && rc != DELAYED_STATUS) {
		rc = min(rc, w_length);
		fsg->ep0req->length = rc;
-		fsg->ep0req->zero = rc < w_length;
+		fsg->ep0req->zero = rc < w_length
+			&& (rc % gadget->ep0->maxpacket) == 0;
		fsg->ep0req_name = (ctrl->bRequestType & USB_DIR_IN ?
				"ep0-in" : "ep0-out");
		rc = ep0_queue(fsg);