On Mon, 25 Mar 2013, David Linares wrote:

> > Start with usbmon (see Documentation/usb/usbmon.txt).
> 
> Thanks Alan. I have just compiled my kernel with debugfs and usbmon.
> I can now easily capture raw text traces after boot-up. But I am interested
> in capturing these traces at boot time because that's when the problems
> occur. Any way to achieve that?

No, there isn't any way.  The best you can do is build the host 
controller driver as a module, and start up usbmon before the module is 
loaded.

> While enabling usbmon, I noticed something that can be related.
> There is a config: "Maximum VBUS Power usage" which is currently set to
> 300mA in my case.

That option (USB_GADGET_VBUS_DRAW) applies only to gadgets.  That is,
it's meant for the part of the USB stack used in peripherals, not in 
hosts.

> But here is the USB dongle I am using:
> 
> lsusb -v
> ...
>   idVendor           0x148f Ralink Technology, Corp.
>   idProduct          0x5370 RT5370 Wireless Adapter
> ..
>   MaxPower              450mA
> 
> I guess setting 450mA will sort out my issue number 4 and avoid the
> "usb 1-1.1: rejected 1 configuration due to insufficient available bus power"
> right?

No, it won't have any effect at all.  What might help would be to plug
the wireless adapter into a powered hub instead of directly into your
computer.

Alan Stern

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