From 6779af1510d6f5412d444aac52c4d5badc912c01 Mon Sep 17 00:00:00 2001 From: Daniel Drake Date: Sat, 7 Nov 2009 12:37:59 +0000 Subject: [PATCH] Add LIBUSB_TRANSFER_ZERO_PACKET (#6) Add a transfer flag useful when working with protocols where logical requests are divided by incomplete packets. Currently only supported on Linux. Based on earlier work by Nikias Bassen. --- libusb/core.c | 9 +++++++++ libusb/io.c | 2 ++ libusb/libusb.h | 27 ++++++++++++++++++++++++++- libusb/os/darwin_usb.c | 3 +++ libusb/os/linux_usbfs.c | 3 +++ libusb/os/linux_usbfs.h | 1 + 6 files changed, 44 insertions(+), 1 deletions(-) diff --git a/libusb/core.c b/libusb/core.c index 7e4fd24..04dcc3e 100644 --- a/libusb/core.c +++ b/libusb/core.c @@ -283,6 +283,15 @@ if (cfg != desired) * kernel where boundaries occur between logical libusb-level transfers. When * a short transfer (or other error) occurs, the kernel will cancel all the * subtransfers until the boundary without allowing those transfers to start. + * + * \section zlp Zero length packets + * + * - libusb is designed to be able to send a packet of zero-length to an + * endpoint simply by submitting a transfer of zero length. On Linux, this did + * not work with libusb versions prior to v1.0.3 and kernel versions prior to + * v2.6.31. + * - The \ref libusb_transfer_flags::LIBUSB_TRANSFER_ZERO_PACKET + * "LIBUSB_TRANSFER_ZERO_PACKET" flag is unsupported on Darwin. */ /** diff --git a/libusb/io.c b/libusb/io.c index 65c2cf4..361057a 100644 --- a/libusb/io.c +++ b/libusb/io.c @@ -1206,6 +1206,8 @@ API_EXPORTED void libusb_free_transfer(struct libusb_transfer *transfer) * \returns 0 on success * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected * \returns LIBUSB_ERROR_BUSY if the transfer has already been submitted. + * \returns LIBUSB_ERROR_NOT_SUPPORTED if the transfer flags are not supported + * by the operating system. * \returns another LIBUSB_ERROR code on other failure */ API_EXPORTED int libusb_submit_transfer(struct libusb_transfer *transfer) diff --git a/libusb/libusb.h b/libusb/libusb.h index 2dbb9a5..b682ee8 100644 --- a/libusb/libusb.h +++ b/libusb/libusb.h @@ -672,7 +672,32 @@ 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, + + /** Terminate transfers that are a multiple of the endpoint's maximum + * packet size with an extra zero-length packet. This is useful when a + * device protocol mandates that each logical request is terminated by + * an incomplete packet (i.e. the logical requests are not separated by + * other means). + * + * This flag only affects host-to-device transfers to bulk and interrupt + * endpoints. In other situations, it is ignored. + * + * This flag only affects transfers with a length that is a multiple of + * the endpoint's packet size. On transfers of other lengths, this flag + * has no effect. Therefore, if you are working with a device that needs + * a ZLP whenever the end of the logical request falls on a packet boundary, + * then it is sensible to set this flag on every transfer (you + * do not have to worry about only setting it on transfers that end on the + * boundary). + * + * This flag is unsupported on Darwin. On Darwin, libusb_submit_transfer() + * will return LIBUSB_ERROR_NOT_SUPPORTED for every transfer where this flag + * is set. + * + * Since v1.0.5. + */ + LIBUSB_TRANSFER_ZERO_PACKET = 1 << 3 }; /** \ingroup asyncio diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c index 9c64b60..9c75ed0 100644 --- a/libusb/os/darwin_usb.c +++ b/libusb/os/darwin_usb.c @@ -1046,6 +1046,9 @@ static int submit_bulk_transfer(struct usbi_transfer *itransfer) { /* are we reading or writing? */ is_read = transfer->endpoint & LIBUSB_ENDPOINT_IN; + + if (!is_read & transfer->flags & LIBUSB_TRANSFER_ZERO_PACKET) + return LIBUSB_ERROR_NOT_SUPPORTED; if (ep_to_pipeRef (transfer->dev_handle, transfer->endpoint, &pipeRef, &iface) != 0) { _usbi_log (TRANSFER_CTX (transfer), LOG_LEVEL_ERROR, "endpoint not found on any open interface"); diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c index ffa4088..f93e0c8 100644 --- a/libusb/os/linux_usbfs.c +++ b/libusb/os/linux_usbfs.c @@ -1376,6 +1376,9 @@ static int submit_bulk_transfer(struct usbi_transfer *itransfer, if (i > 0 && supports_flag_bulk_continuation) urb->flags |= USBFS_URB_BULK_CONTINUATION; + if (transfer->flags & LIBUSB_TRANSFER_ZERO_PACKET && i == num_urbs - 1) + 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 bd02edc..7b737f6 100644 --- a/libusb/os/linux_usbfs.h +++ b/libusb/os/linux_usbfs.h @@ -64,6 +64,7 @@ struct usbfs_getdriver { #define USBFS_URB_ISO_ASAP 0x02 #define USBFS_URB_BULK_CONTINUATION 0x04 #define USBFS_URB_QUEUE_BULK 0x10 +#define USBFS_URB_ZERO_PACKET 0x40 enum usbfs_urb_type { USBFS_URB_TYPE_ISO = 0, -- 1.6.5.2