docs/163646: update man ehci(4) to mention options USB_DEBUG

[Momchil Ivanov]

>Number:         163646
>Category:       docs
>Synopsis:       update man ehci(4) to mention options USB_DEBUG
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Dec 27 17:00:31 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Momchil Ivanov
>Release:        8.2-STABLE
>Organization:
>Environment:
FreeBSD 8.2-STABLE #2: Tue Dec 27 17:01:47 CET 2011 i386
>Description:
The man page of ehci(4) mentions "LOADER TUNABLES" but they are only available after compiling the kernel with "options USB_DEBUG", which is not mentioned. The man page should make it clear that one needs to recompile the kernel with that option or these sysctls should be made availabe without "options USB_DEBUG". Probably the easiest way would be to update the man page and also mention that the sysctl hw.usb.ehci.lostintrbug is highly probable to solve problems with slow devices or ones that get stalled regularly.

For more information refer to the following thread [1].

1: http://lists.freebsd.org/pipermail/freebsd-usb/2011-December/010940.html
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
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