[PATCH v2] usb: gadget: f_hid: Fix zero length packet transfer

[William Wu <william.wu@rock-chips.com>]

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 <william.wu@rock-chips.com>
---
Changelog:

v2:
- set req->zero to 1 instead of check whether the length is divisible by the maxpacket

---
 drivers/usb/gadget/function/f_hid.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index 8e1d1e8..307ea56 100644
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -511,7 +511,7 @@ 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;
@@ -967,7 +967,7 @@ 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)
-- 
2.0.0