Re: [PATCH V2] usb: core: allow zero packet flag for interrupt urbs

From: Alan Stern
Date: Mon Jul 21 2014 - 10:06:42 EST


On Mon, 21 Jul 2014, Amit Virdi wrote:

> Section 4.4.7.2 "Interrupt Transfer Bandwidth Requirements" of the USB3.0 spec
> says:
> A zero-length data payload is a valid transfer and may be useful for
> some implementations.
>
> So, extend the logic of allowing URB_ZERO_PACKET to interrupt urbs too.
> Otherwise, the kernel throws warning of BOGUS transfer flags.
>
> Signed-off-by: Amit Virdi <amit.virdi@xxxxxx>
> Acked-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/usb/core/urb.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> index 991386ceb4ec..c9e8ee81b6b7 100644
> --- a/drivers/usb/core/urb.c
> +++ b/drivers/usb/core/urb.c
> @@ -454,6 +454,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
> URB_FREE_BUFFER);
> switch (xfertype) {
> case USB_ENDPOINT_XFER_BULK:
> + case USB_ENDPOINT_XFER_INT:
> if (is_out)
> allowed |= URB_ZERO_PACKET;
> /* FALLTHROUGH */

Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>

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