On 8/18/20 3:58 AM, Greg Kroah-Hartman wrote: > 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! > Needs to call sched_set_fifo() now. See upstream commit 94beddacb53cd ("sched,watchdog: Convert to sched_set_fifo()"). Guenter > Please fix up and resend against 5.9-rc1. > > thanks, > > greg k-h >