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linux-next/drivers/usb/storage/initializers.h
Bjørn Mork ab4b71644a USB: storage: fix Huawei mode switching regression
This reverts commit 200e0d99 ("USB: storage: optimize to match the
Huawei USB storage devices and support new switch command" and the
followup bugfix commit cd060956 ("USB: storage: properly handle
the endian issues of idProduct").

The commit effectively added a large number of Huawei devices to
the deprecated usb-storage mode switching logic.  Many of these
devices have been in use and supported by the userspace
usb_modeswitch utility for years.  Forcing the switching inside
the kernel causes a number of regressions as a result of ignoring
existing onfigurations, and also completely takes away the ability
to configure mode switching per device/system/user.

Known regressions caused by this:
 - Some of the devices support multiple modes, using different
  switching commands.  There are existing configurations taking
  advantage of this.

 - There is a real use case for disabling mode switching and
  instead mounting the exposed storage device. This becomes
  impossible with switching logic inside the usb-storage driver.

 - At least on device fail as a result of the usb-storage switching
  command, becoming completely unswitchable. This is possibly a
  firmware bug, but still a regression because the device work as
  expected using usb_modeswitch defaults.

In-kernel mode switching was deprecated years ago with the
development of the more user friendly userspace alternatives. The
existing list of devices in usb-storage was only kept to prevent
breaking already working systems.  The long term plan is to remove
the list, not to add to it. Ref:
http://permalink.gmane.org/gmane.linux.usb.general/28543

Cc: <fangxiaozhi@huawei.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-07 12:23:17 +08:00

51 lines
2.1 KiB
C

/* Header file for Special Initializers for certain USB Mass Storage devices
*
* Current development and maintenance by:
* (c) 1999, 2000 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
*
* This driver is based on the 'USB Mass Storage Class' document. This
* describes in detail the protocol used to communicate with such
* devices. Clearly, the designers had SCSI and ATAPI commands in
* mind when they created this document. The commands are all very
* similar to commands in the SCSI-II and ATAPI specifications.
*
* It is important to note that in a number of cases this class
* exhibits class-specific exemptions from the USB specification.
* Notably the usage of NAK, STALL and ACK differs from the norm, in
* that they are used to communicate wait, failed and OK on commands.
*
* Also, for certain devices, the interrupt endpoint is used to convey
* status of a command.
*
* Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
* information about this driver.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "usb.h"
#include "transport.h"
/* This places the Shuttle/SCM USB<->SCSI bridge devices in multi-target
* mode */
int usb_stor_euscsi_init(struct us_data *us);
/* This function is required to activate all four slots on the UCR-61S2B
* flash reader */
int usb_stor_ucr61s2b_init(struct us_data *us);
/* This places the HUAWEI E220 devices in multi-port mode */
int usb_stor_huawei_e220_init(struct us_data *us);