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fea6b53e63
commit 1b7f56fbc7 upstream.
The device initiated link power management U1/U2 states should not be
enabled in case the system exit latency plus one bus interval (125us) is
greater than the shortest service interval of any periodic endpoint.
This is the case for both U1 and U2 sytstem exit latencies and link states.
See USB 3.2 section 9.4.9 "Set Feature" for more details
Note, before this patch the host and device initiated U1/U2 lpm states
were both enabled with lpm. After this patch it's possible to end up with
only host inititated U1/U2 lpm in case the exit latencies won't allow
device initiated lpm.
If this case we still want to set the udev->usb3_lpm_ux_enabled flag so
that sysfs users can see the link may go to U1/U2.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210715150122.1995966-2-mathias.nyman@linux.intel.com
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.