USB: ehci-dbgp: stability improvements and external re-init

USB: ehci-dbgp: stability improvements and external re-init

This patch implements several changes:

1) Improve the capability to debug the dbgp driver

   The dbgp_ehci_status() was added in a number of places to report
   the critical ehci registers to diagnose the cause of a failure of
   the ehci-dbgp driver.

2) Capability to survive the host controller initialization

   The dbgp_external_startup(), dbgp_not_safe, and dbgp_phys_port were
   added so as to allow the ehci-dbgp to re-initialize after the ehci
   host controller is reset by the standard host controller driver.
   This same routine is common for the early startup or
   re-initialization.

   This resulted in the need to move some of the initialization code
   out of the __init section because the ehci driver has the
   possibility to be loaded later on as a kernel module.

3) Stability improvements for device initialization

   The device enumeration from 0 to 127 has the possibility to fail
   the first time after a warm reset on some older EHCI debug
   controllers.  The enumeration will be tried up to 3 times to
   account for this failure case.

   The dbg_wait_until_complete() was changed to wait up to 250 ms
   before failing which only comes into play during device
   initialization. The maximum delay will never get hit during the
   course of normal operation of the driver, unless the device got
   unplugged or there was a ehci controller failure, in which case the
   dbgp device driver will shut itself down.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: dbrownell@users.sourceforge.net
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>