usb: gadget: f_hid: Fix zero length packet transfer

[ Upstream commit ed6f727 ]

Set the hid req->zero flag of ep0/in_ep to true by default,
then the UDC drivers can transfer a zero length packet at
the end if the hid transfer with size divisible to EPs max
packet size according to the USB 2.0 spec.

Signed-off-by: William Wu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
(cherry picked from commit 38c179c52d22272bd5df9d0b14caa6a2e2e3d3e3)
Signed-off-by: Wentao Guan <[email protected]>

Author: wuliangfeng

drivers/usb/gadget/function/f_hid.c

@@ -494,7 +494,7 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer,
 	}
 
 	req->status   = 0;
-	req->zero     = 0;
+	req->zero     = 1;
 	req->length   = count;
 	req->complete = f_hidg_req_complete;
 	req->context  = hidg;
@@ -765,7 +765,7 @@ static int hidg_setup(struct usb_function *f,
 	return -EOPNOTSUPP;
 
 respond:
-	req->zero = 0;
+	req->zero = 1;
 	req->length = length;
 	status = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
 	if (status < 0)