[added to the 3.18 stable tree] usb: gadget: printer: enqueue printer's response for setup request

[Sasha Levin <sasha.levin@oracle.com>]

From: Andrzej Pietrasiewicz <andrzej.p@samsung.com>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit eb132ccbdec5df46e29c9814adf76075ce83576b ]

Function-specific setup requests should be handled in such a way, that
apart from filling in the data buffer, the requests are also actually
enqueued: if function-specific setup is called from composte_setup(),
the "usb_ep_queue()" block of code in composite_setup() is skipped.

The printer function lacks this part and it results in e.g. get device id
requests failing: the host expects some response, the device prepares it
but does not equeue it for sending to the host, so the host finally asserts
timeout.

This patch adds enqueueing the prepared responses.

Cc: <stable@vger.kernel.org> # v3.4+
Fixes: 2e87edf49227: "usb: gadget: make g_printer use composite"
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
 drivers/usb/gadget/legacy/printer.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/gadget/legacy/printer.c b/drivers/usb/gadget/legacy/printer.c
index 6474081..c9c6dae 100644
--- a/drivers/usb/gadget/legacy/printer.c
+++ b/drivers/usb/gadget/legacy/printer.c
@@ -980,6 +980,15 @@ unknown:
 		break;
 	}
 	/* host either stalls (value < 0) or reports success */
+	if (value >= 0) {
+		req->length = value;
+		req->zero = value < wLength;
+		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+		if (value < 0) {
+			ERROR(dev, "%s:%d Error!\n", __func__, __LINE__);
+			req->status = 0;
+		}
+	}
 	return value;
 }
 
-- 
2.1.0