>Date: Mon, 10 Jul 2006 20:07:05 +0530
>From: "Ajay Jain" <[EMAIL PROTECTED]>
>To: linux-usb-devel@lists.sourceforge.net
>Hi,
>Am using a windows host and a proprietary device as a function. This
>is the pre-enumeration stage that I am talking about. I see a very
>different behavior with what is written in the standard or with the
>way windows is supposed to enumerate. The following are the
>observations with CATC protocol analyzer. As I understand, there
>should be a reset followed by a get dev descriptor request and then a
>reset again which will be followed by set address and then no more
>resets for the duration of enumeration. Here I am seeing 4 superfluous
>resets and suspends in the beginning. Is it any windows oddity?
>Ajay
>PS: I only have a clue to the first one, I guess the CATC analyzer s/w
>treats the entire boot-up duration as a reset as well, and that is why
>we see a first long reset for 15 seconds.
>
>Logs
>----------------------------------------------------------
>----------------------------------------------------------
>
>Packet#
>_______|_______________________________________________________________________
>Reset(Reset.) (15.755 sec) Idle( 3.962 ms)
>_______|_______________________________________________________________________
>Suspend(Suspend) (229.459 ms)
>_______|_______________________________________________________________________
>Reset(Reset.) ( 66.487 ms) Idle( 3.005 ms)
>_______|_______________________________________________________________________
>Suspend(Suspend) (198.209 ms)
>_______|_______________________________________________________________________
>Reset(Reset.) ( 48.580 ms) Idle( 3.003 ms)
>_______|_______________________________________________________________________
>Suspend(Suspend) (113.336 ms)
>_______|_______________________________________________________________________
>Reset(Reset.) ( 66.547 ms) Idle( 3.004 ms)
>_______|_______________________________________________________________________
>Suspend(Suspend) (768.334 ms)
>_______|_______________________________________________________________________
>Reset(Reset.) ( 26.288 ms) Idle(761.583 µs)
>_______|_______________________________________________________________________
>54_____| FS Sync(00000001) SETUP(0xB4) ADDR(0) ENDP(0) CRC5(0x08)
EOP(2.75)
>_______| Idle(187 ns)
snip - normal trace from here on.
This is an interesting trace. Think of what is happening on the two data
wires. Reset means both D+,D- are pulled low, this is called single ended
zero (SE0). Idle and suspend are the exact same wire state - J, for a full
speed device J is D+ high, D- low. It is only by spec that the meaning of J
changes from idle to suspend. After 3ms of idle by spec USB devices must go
into lower power suspend, however there is no way for an external analyzer
to verify this.
An analyzer cannot tell the difference between an actively driven bus line
such as SE0 and one where there is no device resistor pulling up the data
line.
So what I think is happening:
This is a trace of the power up of your PC. That takes about 17 seconds.
During that time the Bios and the system software is configuring the
hardware etc. So some of the time the PC is actively driving the lines to
SE0, or some of the times not (where the J state wins). In either case the
host PC is ignoring what is happening on the USB bus.
In normal use the PC will see the J state and start talking to the device,
which is exactly what happens when it finally starts the enumeration.
Every PC/BIOS/OS will probably have a slightly different sequence during its
boot up sequence. I would expect any one instance of PC/BIOS/OS to boot the
same though.
It is not clear to me why you think there is a problem?
Regards, Steve
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