1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
From 13123672fc1edb1e8ce52f60eef045e3c901e5d6 Mon Sep 17 00:00:00 2001
From: Nikias Bassen <nikias@gmx.li>
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
|
