3ed8e1c2ac
"tReceiverResponse 15 ms Section 6.6.2 The receiver of a Message requiring a response Shall respond within tReceiverResponse in order to ensure that the sender’s SenderResponseTimer does not expire." When the cpu complex is busy running other lower priority work items, TCPM's work queue sometimes does not get scheduled on time to meet the above requirement from the spec. Moving to kthread_work apis to run with real time priority. Further, as observed in 1ff688209e2e, moving to hrtimers to overcome scheduling latency while scheduling the delayed work. TCPM has three work streams: 1. tcpm_state_machine 2. vdm_state_machine 3. event_work tcpm_state_machine and vdm_state_machine both schedule work in future i.e. delayed. Hence each of them have a corresponding hrtimer, tcpm_state_machine_timer & vdm_state_machine_timer. When work is queued right away kthread_queue_work is used. Else, the relevant timer is programmed and made to queue the kthread_work upon timer expiry. kthread_create_worker only creates one kthread worker thread, hence single threadedness of workqueue is retained. Signed-off-by: Badhri Jagan Sridharan <badhri@google.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Link: https://lore.kernel.org/r/20200818192758.2562908-1-badhri@google.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.