On Fri, 3 Jul 2015, Peter Chen wrote:
> According to the USB 2.0 Spec CH5.5.3 and CH8.5.3.2, only control
> read (IN) needs zero length packet.
>
> Cc: Alan Stern <st...@rowland.harvard.edu>
> Signed-off-by: Peter Chen <peter.c...@freescale.com>
> ---
> drivers/usb/gadget/composite.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index 1c0c3da..c3898b5 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -1744,7 +1744,8 @@ unknown:
> }
> req->length = value;
> req->context = cdev;
> - req->zero = value < w_length;
> + if (ctrl->bRequestType == USB_DIR_IN)
> + req->zero = value < w_length;
> value = composite_ep0_queue(cdev, req, GFP_ATOMIC);
> if (value < 0) {
> DBG(cdev, "ep_queue --> %d\n", value);
> @@ -1820,7 +1821,8 @@ try_fun_setup:
> if (value >= 0 && value != USB_GADGET_DELAYED_STATUS) {
> req->length = value;
> req->context = cdev;
> - req->zero = value < w_length;
> + if (ctrl->bRequestType == USB_DIR_IN)
> + req->zero = value < w_length;
> value = composite_ep0_queue(cdev, req, GFP_ATOMIC);
> if (value < 0) {
> DBG(cdev, "ep_queue --> %d\n", value);
This change is not needed. A UDC driver is always supposed to ignore
req->zero for OUT transfers. (It also is supposed to ignore req->zero
if req->length == 0 or req->length % maxpacket != 0.)
Alan Stern
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