From 13123672fc1edb1e8ce52f60eef045e3c901e5d6 Mon Sep 17 00:00:00 2001 From: Nikias Bassen Date: Sat, 5 Sep 2009 15:42:01 +0200 Subject: [PATCH] New flag LIBUSB_TRANSFER_ZERO_PACKET for bulk/interrupt transfers. This flag will let the kernel append an additional zero-length packet to a tansfer. This is required for certain devices when sending packets with a size that is a multiple of wMaxPacketSize. --- libusb/libusb.h | 18 +++++++++++++++++- libusb/os/linux_usbfs.c | 3 +++ libusb/os/linux_usbfs.h | 1 + 3 files changed, 21 insertions(+), 1 deletions(-) diff --git a/libusb/libusb.h b/libusb/libusb.h index 1126380..bf7f02d 100644 --- a/libusb/libusb.h +++ b/libusb/libusb.h @@ -672,7 +672,23 @@ enum libusb_transfer_flags { * If this flag is set, it is illegal to call libusb_free_transfer() * from your transfer callback, as this will result in a double-free * when this flag is acted upon. */ - LIBUSB_TRANSFER_FREE_TRANSFER = 1<<2 + LIBUSB_TRANSFER_FREE_TRANSFER = 1<<2, + + /** If this flag is set, a zero-length packet will be appended to + * the transfer indicating that the transfer is complete. + * Some devices require to be notified when a transfer is complete. + * Usually a device knows about the end of the transfer if the last + * packet's size is less than wMaxPacketSize. + * But if the last packet of a transfer has _exactly_ the size of + * wMaxPacketSize, the device does not know that it is the last + * packet. This is where a zero-length packet is required, which + * will let the device know that the transfer is complete. + * + * This flag is valid for the following transfer types: + * LIBUSB_TRANSFER_TYPE_BULK + * LIBUSB_TRANSFER_TYPE_INTERRUPT + */ + LIBUSB_TRANSFER_ZERO_PACKET = 1<<3 }; /** \ingroup asyncio diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c index 1280188..816bcbf 100644 --- a/libusb/os/linux_usbfs.c +++ b/libusb/os/linux_usbfs.c @@ -1307,6 +1307,9 @@ static int submit_bulk_transfer(struct usbi_transfer *itransfer, else urb->buffer_length = MAX_BULK_BUFFER_LENGTH; + if (i == num_urbs -1 && (transfer->flags & LIBUSB_TRANSFER_ZERO_PACKET)) + urb->flags |= USBFS_URB_ZERO_PACKET; + r = ioctl(dpriv->fd, IOCTL_USBFS_SUBMITURB, urb); if (r < 0) { int j; diff --git a/libusb/os/linux_usbfs.h b/libusb/os/linux_usbfs.h index fdf5e9b..9ed0b4f 100644 --- a/libusb/os/linux_usbfs.h +++ b/libusb/os/linux_usbfs.h @@ -63,6 +63,7 @@ struct usbfs_getdriver { #define USBFS_URB_DISABLE_SPD 1 #define USBFS_URB_ISO_ASAP 2 #define USBFS_URB_QUEUE_BULK 0x10 +#define USBFS_URB_ZERO_PACKET 0x40 enum usbfs_urb_type { USBFS_URB_TYPE_ISO = 0, -- 1.6.0.4