Re: [PATCH, RFC] USBIP protocol documentation

From: Németh Márton
Date: Thu Jun 30 2011 - 15:39:42 EST

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In reply to: Matt Chen: "Re: [PATCH, RFC] USBIP protocol documentation"
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Matt Chen wrote:
> Hi Németh and Matt,
> We are also working on reviewing protocol here. We were wondering if
> you are available for letting us know which part you've already done.
> Then we can save the time for doing the same parts.

I've already sent everything I have. Nothing remained unsent from my side.

> And also we would like to follow your suggesting format to work on it.
> Then it would make it work much faster.
> Any suggestion ?
>
> 2011/6/30 Németh Márton <nm127@xxxxxxxxxxx>
>> Matt Chen wrote:
>>> Hi Matt,
>>>
>>>
>>> 2011/6/30 matt mooney <mfm@xxxxxxxxxxxxx <mailto:mfm@xxxxxxxxxxxxx>>:
>>>> On 08:52 Tue 28 Jun , N??meth M??rton wrote:
>>>>> From: M??rton N??meth <nm127@xxxxxxxxxxx <mailto:nm127@xxxxxxxxxxx>>
>>>>>
>>>>> USBIP v1.0.0 protocol documentation.
>>>>>
>>>>> Signed-off-by: M??rton N??meth <nm127@xxxxxxxxxxx
>>> <mailto:nm127@xxxxxxxxxxx>>
>>>>> ---
>>>>>
>>>>> Hi,
>>>>>
>>>>> I tried to document the USBIP protocol as implemented in the Linux
>>> kernel 3.0-rc2.
>>>> Yeah, thanks for doing this. I am also documenting the protocol but am not
>>>> finished yet. We can use yours as the base if you would like although
>>> I have a
>>>> few suggestions.
>>>>
>>>> For one, the grammar needs to be cleaned up, but instead of me
>>> pointing out all
>>>> of the needed corrections, I will send in a grammar corrections patch
>>> on top of
>> Please go on with the corrections. I really started documenting the
>> current USBIP protocol because I think digging in the source code is
>> not the right way to describe a protocol. I'm happy that the review
>> of the USBIP protocol description started. Once we have documented the current
>> USBIP protocol I think we'll see more clearly its weaknesses.
>>
>> What I think important to include in the protocol description is to
>> identify the unused fields and specify an exact value (usually zero) to
>> use for these fields. This makes possible future extension of the protocol
>> easy.
>>
>> One more random thing which came to my mind is that I tend to think that
>> the current implementation is buggy when ISO packets are transmitted.
>> I have a hama AC-150 webcam which is not working well with USBIP. This
>> webcam usually sends smaller ISO packets so there is a gap between
>> the ISO packets in one single URB. The problem came up already in case
>> of usbmon, see https://bugzilla.kernel.org/show_bug.cgi?id=22182 and
>> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b17ea167c5fb50dcd5dce5b874a467f04eec886d
>> .
>>
>>>> the finished document. I like that you did a time sequence diagram,
>>> which is
>>>> something I had neglected to include myself; however, I am not a big
>>> fan of how
>>>> you laid out the messages. I was planning on using packet diagrams.
>>> IMHO, it
>>>> makes understanding the message composition much easier allowing more
>>> insight to
>>>> be gathered from a cursory glance.
>>>>
>>>>
>>>> Message Format
>>>> --------------
>>>> 0 1 2 3
>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>> | Version | Opcode |
>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>> | Status |
>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>> . .
>>>> . Data .
>>>> . .
>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>>
>>>> Version: 16 bit
>>>> Binary-coded decimal version number of the usbip-utils package from
>>>> which the program was built.
>>>>
>>>> Opcode: 16 bits
>>>> ...
>>>>
>>> So as you mentioned, the message format is looked like below:
>>>
>>> OP_REQ_DEVLIST Message Format
>>>
>>> 0 1 2
>>> 3 4
>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>> | 0000 0000 1000 0000 | 1000 0000 0000 0101 |
>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
>>> | 0000 0000 0000 0000 0000 0000 0000 0000 |
>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
>>>
>>> Is this correct ?
>>>
>>> Personally, I like this way to describe the protocol. ;-)
>> This layout format what is used in other RFCs, too, is really a better
>> way to show the messages. I think, however, that we don't need to put
>> the values in binary format, we could just put one hexadecimal number
>> in the gaps, like this:
>>
>> OP_REQ_DEVLIST Message Format
>>
>>
>> 0 1 2 3
>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>> | 0x0100 | 0x8005 |
>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>> | 0x00000000 |
>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>>>> As you may or may not see, I was going to take a more generic approach
>>> and then
>>>> describe the fields on a per-op basis. Of course, the main point here
>>> is that
>>>> the protocol is documented, so I am not opposed to a different style
>>> being used.
>>>> But if you insist on the current layout, do not put a value for the
>>> version
>>>> because it is not constant (and in fact no longer at 1.0.0). And the
>>> "Meaning"
>>>> header should be "Description" or something better.
>>>>
>>>> Hmm, taking another look the layout just seems to busy... I really do
>>> think we
>>>> should find a different way to format the information.
>>>>
>>>> Thanks,
>>>> matt
>>>>
>>>>> The description is a preliminary draft only, it may contain mistakes.
>>> I tried
>>>>> to document what I have understand from the source code and from the
>>> actual
>>>>> captured network traffic when the USBIP is in action. Please review
>>> it, correct it,
>>>>> point out the missing parts.
>>>>>
>>>>> During I have documented the protocol a question came into my mind:
>>> why do we
>>>>> have two different type of package when the URB completition handler
>>> is called,
>>>>> namely USB_RET_SUBMIT and USBIP_RET_UNLINK? As far as I can see this
>>> causes race
>>>>> condition because for one URB the completition handler is only called
>>> once. If
>>>>> the one URB is sent in with USB_CMD_SUBMIT and then unlinked with
>>> USB_CMD_UNLINK
>>>>> the completition handler is called only once. In the protocol,
>>> however, we have
>>>>> two different type of packets: USB_RET_SUBMIT and USBIP_RET_UNLINK.
>>> The status
>>>>> field of these messages may contain anything in this case depending
>>> on the timing.
>>>>> Regards,
>>>>>
>>>>> M??rton N??meth
>>>>> ---
>>>>> diff -uprN staging-2.6.orig/drivers/staging/usbip/usbip_protocol.txt
>>> staging-2.6/drivers/staging/usbip/usbip_protocol.txt
>>>>> --- staging-2.6.orig/drivers/staging/usbip/usbip_protocol.txt
>>> 1970-01-01 01:00:00.000000000 +0100
>>>>> +++ staging-2.6/drivers/staging/usbip/usbip_protocol.txt
>>> 2011-06-28 08:30:04.000000000 +0200
>>>>> @@ -0,0 +1,352 @@
>>>>> +PRELIMINARY DRAFT, MAY CONTAIN MISTAKES!
>>>>> +28 Jun 2011
>>>>> +
>>>>> +The USB/IP protocol follows a server/client architecture. The server
>>> exports the
>>>>> +USB devices and the clients imports them. The device driver for the
>>> exported
>>>>> +USB device runs on the client machine.
>>>>> +
>>>>> +The client may ask for the list of the exported USB devices. To get
>>> the list the
>>>>> +client opens a TCP/IP connection towards the server, and sends an
>>> OP_REQ_DEVLIST
>>>>> +packet on top of the TCP/IP connection (so the actual OP_REQ_DEVLIST
>>> may be sent
>>>>> +in one or more pieces at the low level transport layer). The server
>>> sends back
>>>>> +the OP_REP_DEVLIST packet which lists the exported USB devices.
>>> Finally the
>>>>> +TCP/IP connection is closed.
>>>>> +
>>>>> + virtual host controller usb host
>>>>> + "client" "server"
>>>>> + (imports USB devices) (exports USB
>>> devices)
>>>>> + | |
>>>>> + | OP_REQ_DEVLIST |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | OP_REP_DEVLIST |
>>>>> + | <---------------------------------------------- |
>>>>> + | |
>>>>> +
>>>>> +Once the client knows the list of exported USB devices it may decide
>>> to use one
>>>>> +of them. First the client opens a TCP/IP connection towards the
>>> server and
>>>>> +sends an OP_REQ_IMPORT packet. The server replies with
>>> OP_REP_IMPORT. If the
>>>>> +import was successful the TCP/IP connection remains open and will be
>>> used
>>>>> +to trasfer the URB traffic between the client and the server. The
>>> client may
>>>>> +send two types of packets: the USBIP_CMD_SUBMIT to submit an URB, and
>>>>> +USBIP_CMD_UNLINK to unlink a previously submitted URB. The answers
>>> of the
>>>>> +server may be USBIP_RET_SUBMIT and USBIP_RET_UNLINK respectively.
>>>>> +
>>>>> + virtual host controller usb host
>>>>> + "client" "server"
>>>>> + (imports USB devices) (exports USB
>>> devices)
>>>>> + | |
>>>>> + | OP_REQ_IMPORT |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | OP_REP_IMPORT |
>>>>> + | <---------------------------------------------- |
>>>>> + | |
>>>>> + | |
>>>>> + | USBIP_CMD_SUBMIT(seqnum = n) |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | USBIP_RET_SUBMIT(seqnum = n) |
>>>>> + | <---------------------------------------------- |
>>>>> + | . |
>>>>> + | : |
>>>>> + | |
>>>>> + | USBIP_CMD_SUBMIT(seqnum = m) |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | USBIP_CMD_SUBMIT(seqnum = m+1) |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | USBIP_CMD_SUBMIT(seqnum = m+2) |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | USBIP_RET_SUBMIT(seqnum = m) |
>>>>> + | <---------------------------------------------- |
>>>>> + | |
>>>>> + | USBIP_CMD_SUBMIT(seqnum = m+3) |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | USBIP_RET_SUBMIT(seqnum = m+1) |
>>>>> + | <---------------------------------------------- |
>>>>> + | |
>>>>> + | USBIP_CMD_SUBMIT(seqnum = m+4) |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | USBIP_RET_SUBMIT(seqnum = m+2) |
>>>>> + | <---------------------------------------------- |
>>>>> + | . |
>>>>> + | : |
>>>>> + | |
>>>>> + | USBIP_CMD_UNLINK |
>>>>> + | ----------------------------------------------> |
>>>>> + | |
>>>>> + | USBIP_RET_UNLINK |
>>>>> + | <---------------------------------------------- |
>>>>> + | |
>>>>> +
>>>>> +The fields are in network (big endian) byte order meaning that the
>>> most significant
>>>>> +byte (MSB) is stored at the lowest address.
>>>>> +
>>>>> +
>>>>> +OP_REQ_DEVLIST: Retrieve the list of exported USB devices.
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 2 | 0x0100 | Binary-coded decimal USBIP
>>> version number: v1.0.0
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 2 | 2 | 0x8005 | Command code: Retrieve the list
>>> of exported USB
>>>>> + | | | devices.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | 0x00000000 | Status: unused, shall be set to 0
>>>>> +
>>>>> +OP_REP_DEVLIST: Reply with the list of exported USB devices.
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 2 | 0x0100 | Binary-coded decimal USBIP
>>> version number: v1.0.0.
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 2 | 2 | 0x0005 | Reply code: The list of exported
>>> USB devices.
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | 0x00000000 | Status: 0 for OK
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 8 | 4 | n | Number of exported devices: 0
>>> means no exported
>>>>> + | | | devices.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x0C | | | From now on the exported n
>>> devices are described,
>>>>> + | | | if any. If no devices are
>>> exported the message
>>>>> + | | | ends with the previous "number
>>> of exported
>>>>> + | | | devices" field.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + | 256 | | path: Path of the device on the
>>> host exporting the
>>>>> + | | | USB device, string closed with
>>> zero byte, e.g.
>>>>> + | | |
>>> "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2"
>>>>> + | | | The unused bytes shall be
>>> filled with zero
>>>>> + | | | bytes.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x10C | 32 | | busid: Bus ID of the exported
>>> device, string
>>>>> + | | | closed with zero byte, e.g.
>>> "3-2". The unused
>>>>> + | | | bytes shall be filled with zero
>>> bytes.
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x12C | 4 | | busnum
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x130 | 4 | | devnum
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x134 | 4 | | speed
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x138 | 2 | | idVendor
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13A | 2 | | idProduct
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13C | 2 | | bcdDevice
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13E | 1 | | bDeviceClass
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13F | 1 | | bDeviceSubClass
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x140 | 1 | | bDeviceProtocol
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x141 | 1 | | bConfigurationValue
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x142 | 1 | | bNumConfigurations
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x143 | 1 | | bNumInterfaces
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x144 | | m_0 | From now on each interface is
>>> described, all
>>>>> + | | | together bNumInterfaces times,
>>> with the
>>>>> + | | | the following 4 fields:
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + | 1 | | bInterfaceClass
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x145 | 1 | | bInterfaceSubClass
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x146 | 1 | | bInterfaceProtocol
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x147 | 1 | | padding byte for alignment, shall
>>> be set to zero
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0xC + | | | The second exported USB device
>>> starts at i=1
>>>>> + i*0x138 + | | | with the busid field.
>>>>> + m_(i-1)*4 | | |
>>>>> +
>>>>> +OP_REQ_IMPORT: Request to import (attach) a remote USB device.
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 2 | 0x0100 | Binary-coded decimal USBIP
>>> version number: v1.0.0
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 2 | 2 | 0x8003 | Command code: import a remote USB
>>> device.
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | 0x00000000 | Status: unused, shall be set to 0
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 8 | 32 | | busid: the busid of the exported
>>> device on the
>>>>> + | | | remote host. The possible
>>> values are taken
>>>>> + | | | from the message field
>>> OP_REP_DEVLIST.busid.
>>>>> + | | | A string closed with zero, the
>>> unused bytes
>>>>> + | | | shall be filled with zeros.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> +
>>>>> +OP_REP_IMPORT: Reply to import (attach) a remote USB device.
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 2 | 0x0100 | Binary-coded decimal USBIP
>>> version number: v1.0.0
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 2 | 2 | 0x0003 | Reply code: Reply to import.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | 0x00000000 | Status: 0 for OK
>>>>> + | | | 1 for error
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 8 | | | From now on comes the details of
>>> the imported
>>>>> + | | | device, if the previous status
>>> field was OK (0),
>>>>> + | | | otherwise the reply ends with
>>> the status field.
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + | 256 | | path: Path of the device on the
>>> host exporting the
>>>>> + | | | USB device, string closed with
>>> zero byte, e.g.
>>>>> + | | |
>>> "/sys/devices/pci0000:00/0000:00:1d.1/usb3/3-2"
>>>>> + | | | The unused bytes shall be
>>> filled with zero
>>>>> + | | | bytes.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x108 | 32 | | busid: Bus ID of the exported
>>> device, string
>>>>> + | | | closed with zero byte, e.g.
>>> "3-2". The unused
>>>>> + | | | bytes shall be filled with zero
>>> bytes.
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x128 | 4 | | busnum
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x12C | 4 | | devnum
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x130 | 4 | | speed
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x134 | 2 | | idVendor
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x136 | 2 | | idProduct
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x138 | 2 | | bcdDevice
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x139 | 1 | | bDeviceClass
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13A | 1 | | bDeviceSubClass
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13B | 1 | | bDeviceProtocol
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13C | 1 | | bConfigurationValue
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13D | 1 | | bNumConfigurations
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x13E | 1 | | bNumInterfaces
>>>>> +
>>>>> +USBIP_CMD_SUBMIT: Submit an URB
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 4 | 0x00000001 | command: Submit an URB
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | | seqnum: the sequence number of
>>> the URB to submit
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 8 | 4 | | devid
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0xC | 4 | | direction: 0: USBIP_DIR_IN
>>>>> + | | | 1: USBIP_DIR_OUT
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x10 | 4 | | ep: endpoint number, possible
>>> values are: 0...15
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x14 | 4 | | transfer_flags: possible values
>>> depend on the
>>>>> + | | | URB transfer type, see below
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x18 | 4 | | transfer_buffer_length
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x1C | 4 | | start_frame: specify the selected
>>> frame to
>>>>> + | | | transmit an ISO frame, ignored
>>> if URB_ISO_ASAP
>>>>> + | | | is specified at transfer_flags
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x20 | 4 | | number_of_packets: number of ISO
>>> packets
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x24 | 4 | | interval: maximum time for the
>>> request on the
>>>>> + | | | server-side host controller
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x28 | 8 | | setup: data bytes for USB setup,
>>> filled with
>>>>> + | | | zeros if not used
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x30 | | | URB data. For ISO transfers the
>>> padding between
>>>>> + | | | each ISO packets is not
>>> transmitted.
>>>>> +
>>>>> +
>>>>> + Allowed transfer_flags | value | control | interrupt | bulk
>>> | isochronous
>>>>> +
>>> -------------------------+------------+---------+-----------+----------+-------------
>>>>> + URB_SHORT_NOT_OK | 0x00000001 | only in | only in | only
>>> in | no
>>>>> + URB_ISO_ASAP | 0x00000002 | no | no | no
>>> | yes
>>>>> + URB_NO_TRANSFER_DMA_MAP | 0x00000004 | yes | yes | yes
>>> | yes
>>>>> + URB_NO_FSBR | 0x00000020 | yes | no | no
>>> | no
>>>>> + URB_ZERO_PACKET | 0x00000040 | no | no | only
>>> out | no
>>>>> + URB_NO_INTERRUPT | 0x00000080 | yes | yes | yes
>>> | yes
>>>>> + URB_FREE_BUFFER | 0x00000100 | yes | yes | yes
>>> | yes
>>>>> + URB_DIR_MASK | 0x00000200 | yes | yes | yes
>>> | yes
>>>>> +
>>>>> +
>>>>> +USBIP_RET_SUBMIT: Reply for submitting an URB
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 4 | 0x00000002 | command
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | | seqnum: URB sequence number
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 8 | 4 | | devid
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0xC | 4 | | direction: 0: USBIP_DIR_IN
>>>>> + | | | 1: USBIP_DIR_OUT
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x10 | 4 | | ep: endpoint number
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x14 | 4 | | status: zero for successful URB
>>> transaction,
>>>>> + | | | otherwise some kind of error
>>> happened.
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x18 | 4 | n | actual_length: number of URB data
>>> bytes
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x1C | 4 | | start_frame: for an ISO frame the
>>> actually
>>>>> + | | | selected frame for transmit.
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x20 | 4 | | number_of_packets
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x24 | 4 | | error_count
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x28 | 8 | | setup: data bytes for USB setup,
>>> filled with
>>>>> + | | | zeros if not used
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x30 | n | | URB data bytes. For ISO transfers
>>> the padding
>>>>> + | | | between each ISO packets is not
>>> transmitted.
>>>>> +
>>>>> +USBIP_CMD_UNLINK: Unlink an URB
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 4 | 0x00000003 | command: URB unlink command
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | | seqnum: URB sequence number to
>>> unlink: FIXME: is this so?
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 8 | 4 | | devid
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0xC | 4 | | direction: 0: USBIP_DIR_IN
>>>>> + | | | 1: USBIP_DIR_OUT
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x10 | 4 | | ep: endpoint number: zero
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x14 | 4 | | seqnum: the URB sequence number
>>> given previously
>>>>> + | | | at USBIP_CMD_SUBMIT.seqnum field
>>>>> +
>>>>> +USBIP_RET_UNLINK: Reply for URB unlink
>>>>> +
>>>>> + Offset | Length | Value | Meaning
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0 | 4 | 0x00000004 | command: reply for the URB unlink
>>> command
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 4 | 4 | | seqnum: the unlinked URB sequence
>>> number
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 8 | 4 | | devid
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0xC | 4 | | direction: 0: USBIP_DIR_IN
>>>>> + | | | 1: USBIP_DIR_OUT
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x10 | 4 | | ep: endpoint number
>>>>>
>>> +-----------+--------+------------+---------------------------------------------------
>>>>> + 0x14 | 4 | | status: This is the value
>>> contained in the
>>>>> + | | | urb->status in the URB
>>> completition handler.
>>>>> + | | | FIXME: a better explanation needed.
>>>>>
>>>> _______________________________________________
>>>> devel mailing list
>>>> devel@xxxxxxxxxxxxxxxxxxxxxx <mailto:devel@xxxxxxxxxxxxxxxxxxxxxx>
>>>> http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
>>>>
>>>
>>>
>>> --
>>> Thanks ~
>>> Matt Chen
>>>
>>>
>>>
>
>
>
> --
> Thanks ~
> Matt Chen
>
>

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