tree f1c0ee0123d7c64b4b15e84b480827896863406c
parent 4b0b870b21ebf5e0f90e7cd5fb2c13274b2daa66
author Alan Stern <stern@rowland.harvard.edu> 1368026285 -0400
committer Matthias Kaehlcke <mka@google.com> 1433366103 -0700

USB: xHCI: override bogus bulk wMaxPacketSize values

commit e4f47e3675e6f1f40906b785b934ce963e9f2eb3 upstream.

This patch shortens the logic in xhci_endpoint_init() by moving common
calculations involving max_packet and max_burst outside the switch
statement, rather than repeating the same code in multiple
case-specific statements.  It also replaces two usages of max_packet
which were clearly intended to be max_burst all along.

More importantly, it compensates for a common bug in high-speed bulk
endpoint descriptors.  In many devices there is a bulk endpoint having
a wMaxPacketSize value smaller than 512, which is forbidden by the USB
spec.  Some xHCI controllers can't handle this and refuse to accept
the endpoint.  This patch changes the max_packet value to 512, which
allows the controller to use the endpoint properly.

In practice the bogus maxpacket size doesn't matter, because none of
the transfers sent via these endpoints are longer than the maxpacket
value anyway.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: "Aurélien Leblond" <blablack@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>