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Commit bd0e6c9614b9 ("usb: hub: try old enumeration scheme first for
high speed devices") changed the way the hub driver enumerates
high-speed devices. Instead of using the "new" enumeration scheme
first and switching to the "old" scheme if that doesn't work, we start
with the "old" scheme. In theory this is better because the "old"
scheme is slightly faster -- it involves resetting the device only
once instead of twice.
However, for a long time Windows used only the "new" scheme. Zeng Tao
said that Windows 8 and later use the "old" scheme for high-speed
devices, but apparently there are some devices that don't like it.
William Bader reports that the Ricoh webcam built into his Sony Vaio
laptop not only doesn't enumerate under the "old" scheme, it gets hung
up so badly that it won't then enumerate under the "new" scheme! Only
a cold reset will fix it.
Therefore we will revert the commit and go back to trying the "new"
scheme first for high-speed devices.
Reported-and-tested-by: William Bader <williambader@hotmail.com>
Ref: https://bugzilla.kernel.org/show_bug.cgi?id=207219
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Fixes: bd0e6c9614b9 ("usb: hub: try old enumeration scheme first for high speed devices")
CC: Zeng Tao <prime.zeng@hisilicon.com>
CC: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.2004221611230.11262-100000@iolanthe.rowland.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.