Revision 9e61d12bac206e5e70176734604371ac3a6e50fd authored by Linus Torvalds on 24 May 2020, 17:14:58 UTC, committed by Linus Torvalds on 24 May 2020, 17:14:58 UTC
Pull scheduler fixes from Thomas Gleixner: "A set of fixes for the scheduler: - Fix handling of throttled parents in enqueue_task_fair() completely. The recent fix overlooked a corner case where the first iteration terminates due to an entity already being on the runqueue which makes the list management incomplete and later triggers the assertion which checks for completeness. - Fix a similar problem in unthrottle_cfs_rq(). - Show the correct uclamp values in procfs which prints the effective value twice instead of requested and effective" * tag 'sched-urgent-2020-05-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list sched/debug: Fix requested task uclamp values shown in procfs sched/fair: Fix enqueue_task_fair() warning some more
dwc3.rst
===========
DWC3 driver
===========
TODO
~~~~
Please pick something while reading :)
- Convert interrupt handler to per-ep-thread-irq
As it turns out some DWC3-commands ~1ms to complete. Currently we spin
until the command completes which is bad.
Implementation idea:
- dwc core implements a demultiplexing irq chip for interrupts per
endpoint. The interrupt numbers are allocated during probe and belong
to the device. If MSI provides per-endpoint interrupt this dummy
interrupt chip can be replaced with "real" interrupts.
- interrupts are requested / allocated on usb_ep_enable() and removed on
usb_ep_disable(). Worst case are 32 interrupts, the lower limit is two
for ep0/1.
- dwc3_send_gadget_ep_cmd() will sleep in wait_for_completion_timeout()
until the command completes.
- the interrupt handler is split into the following pieces:
- primary handler of the device
goes through every event and calls generic_handle_irq() for event
it. On return from generic_handle_irq() in acknowledges the event
counter so interrupt goes away (eventually).
- threaded handler of the device
none
- primary handler of the EP-interrupt
reads the event and tries to process it. Everything that requires
sleeping is handed over to the Thread. The event is saved in an
per-endpoint data-structure.
We probably have to pay attention not to process events once we
handed something to thread so we don't process event X prio Y
where X > Y.
- threaded handler of the EP-interrupt
handles the remaining EP work which might sleep such as waiting
for command completion.
Latency:
There should be no increase in latency since the interrupt-thread has a
high priority and will be run before an average task in user land
(except the user changed priorities).
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