When disconnecting a USB hub that has some child device(s) connected to it
(such as a USB mouse), then the stack tries to clear halt and
reset device(s) which are _already_ physically disconnected.

The issue has been reproduced with:

CPU: IMX6D5EYM10AD or MCIMX6D5EYM10AE.
SW: U-Boot 2019.07 and kernel 4.19.40.

CPU: HP Proliant Microserver Gen8.
SW: Linux version 4.2.3-300.fc23.x86_64

In this situation there will be error bit for MMF active yet the
CERR equals EHCI_TUNE_CERR + halt. Existing implementation
interprets this as a stall [1] (chapter 8.4.5).

The possible conditions when the MMF will be active + halt
can be found from [2] (Table 4-13).

Fix for the issue is to check whether MMF is active and PID Code is
IN before checking for the stall. If these conditions are true then
it is not a stall.

What happens after the fix is that when disconnecting a hub with
attached device(s) the situation is not interpret as a stall.

[1] [https://www.usb.org/document-library/usb-20-specification, usb_20.pdf]
[2] [https://www.intel.com/content/dam/www/public/us/en/documents/
     technical-specifications/ehci-specification-for-usb.pdf]
Signed-off-by: Erkka Talvitie <erkka.talvitie@vincit.fi>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/ef70941d5f349767f19c0ed26b0dd9eed8ad81bb.1576050523.git.erkka.talvitie@vincit.fiSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>