Re: [libusb] multiple usb3 camera issues

[michel <dia...@ya...>]

I'm also facing  disconnect  issue with latest Intel chip set on win-7 (not
tried linux nor win 8/10 xp)
In my case  it is related to power management and some weakness or "bug"  in
the device or host  and incapacity to disable host controller power
management in the  driver (despite all power management is disable in device
control panel)

Quite fast after starting xfers and so fast and repeated transition form u0
to ux power down state the link training fail and time out why device
disconnect. 

see LTSSM  
http://www.totalphase.com/support/articles/200349256-USB-Background
https://www.mindshare.com/files/resources/PLX_USB_PowerManagement_AppNote.pdf

You'll see that LTSSM state machine  as many way to fail and return to SS
inactive in "SS"  (mean disconnected )

They are many such issues with early usb3.0 external Hard disk box likely
also due to poorly supported Power management in erly day and first SS
device controller 
So it may be just that most Linux box/kenrel  just don't do any USB power
management so not facing any such issue . 

>From my experience starting in 2012
First NEC and TI controller driver i tried where not doing any bus level
power management in Win7. 
the latest  driver does but you can disable it and it work around most of
the issue  . 
Look like Intel controelr that came only later driver doesn't  fully disable
PM  why some HDD provider released  f/w upgraded to solve the issues :( 

Since Kernel 3.3 and up to 3.6 i have used the Linux Ti XHCI driver is not
doing any Power management at all and i never faced any issue but the leak . 





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