On Thu, Jul 30, 2020 at 11:58:30PM -0700, Badhri Jagan Sridharan wrote: > "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. > Just lower than the default threaded irq priority, > MAX_USER_RT_PRIO/2 + 1. (Higher number implies lower 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@xxxxxxxxxx> > Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx> > Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > --- With this patch applied I get the following build breakage: ERROR: modpost: "sched_setscheduler" [drivers/usb/typec/tcpm/tcpm.ko] undefined! Please fix up and resend against 5.9-rc1. thanks, greg k-h
