>Date: Tue, 27 Dec 2005 09:12:44 -0800
>
>
>> So then, when I "eject" an USB device in M$ Windows, what actually
happens is not a "power off"
>> the device, but a "suspend" the device ?
>
>What happens when you throw a USB bus monitor on it? They probably would
>at least quiesce all the drivers using the device and suspend and/or
disable
>that device's port, but they might also power it off if the hub allows.
The
>downside of powering down that port is that most USB hardware doesn't
then
>know how to report device connection. (The OTG "Session Request
Protocol"
>would do it, but most non-OTG hardware doesn't support it.)
From the Kitty USB Analyzer:
frame # 810 f=12001 sync 30772 SOF(xa5) frame 810 crc5 0x5 f=0
frame # 811 f=12002 sync 30780 SOF(xa5) frame 811 crc5 0x1a f=0
frame # 812 f=12002 sync 30788 SOF(xa5) frame 812 crc5 0x15 f=0
frame # 813 f=12002 sync 30796 SOF(xa5) frame 813 crc5 0xa f=0
BUS timeout 100ms SE0 30804
BUS timeout 100ms SE0 30806
BUS timeout 100ms SE0 30808
BUS timeout 100ms SE0 30810
BUS timeout 100ms SE0 30812
BUS timeout 100ms SE0 30814
And so on forever....
These results are from my "WinXP Home" laptop of a full speed USB flash
drive. I pushed the "safely remove hardware" button, while tracing the bus.
The button appears in that tray on the bottom by the clock.
SE0 is when both D+ and D- are low which in differential signalling means
single ended zero. So on my root hub ohci port, Windows is putting the
device in reset. My volt/Ohm meter says there is still +5, which I guess is
so a removal and reattach would be detected?
When the eject button is pressed (from Windows exploder), it does something
different! It appears windows just quits talking to the device. (I presume
it flushes any unwritten data first, but I havent caught that, because
windows treats USB flash a a removable device and doesn't cache unwritten
sectors.)
This means that the eject command, while connected to the ohci root hub, the
SOFs keep going out on the lines to the flash device, but windows stops
talking to it.
HTH - Regards Steve
-------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc. Do you grep through log files
for problems? Stop! Download the new AJAX search engine that makes
searching your log files as easy as surfing the web. DOWNLOAD SPLUNK!
http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click
_______________________________________________
[email protected]
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
