Make out-of-band testing (send a packet when its traffic class gate is
closed, expecting it to be delayed) more predictable by allowing the
window size to be customized by isochron_do().
From man isochron-send, the window size alters the advance time (the
delta between the transmission time of the packet, and its expected TX
time when using SO_TXTIME or tc-taprio on the sender). In absence of the
argument, isochron-send defaults to maximizing the advance time (making
it equal to the cycle length).
The default behavior is exactly what is problematic. An advance time
that is too large will make packets intended to be out-of-band still be
potentially in-band with an open gate from the schedule's previous cycle.
We need to allow that advance time to be reduced.
Perhaps a bit confusingly, isochron_do() has a shift_time argument
currently, but that does not help here. The shift time shifts both the
user space wakeup time and the expected TX time by equal amounts, it is
unable of bringing them closer to one another.
Set the window size properly for the Ocelot PSFP selftest as well.
That used to work due to a very carefully chosen SHIFT_TIME_NS.
I've re-tested that the test still works properly.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250426144859.3128352-4-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We can make the phc2sys helper not only synchronize a PHC to
CLOCK_REALTIME, which is what it currently does, but also CLOCK_REALTIME
to a PHC, which is going to be needed in distributed TSN tests.
Instead of making the complexity of the arguments passed to
phc2sys_start() explode, we can let it figure out the sync direction
automatically, based on ptp4l's port states.
Towards that goal, pass just the path to the desired ptp4l instance's
UNIX domain socket, and remove the $if_name argument (from which it
derives the PHC). Also adapt the one caller from the ocelot psfp.sh
test. In the case of psfp.sh, phc2sys_start is able to properly figure
out that CLOCK_REALTIME is the source clock and swp1's PHC is the
destination, because of the way in which ptp4l_start for the
UDS_ADDRESS_SWP1 was called: with slave_only=false, so it will always
win the BMCA and always become the sync master between itself and $h1.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The Felix VSC9959 switch in NXP LS1028A supports the tc-gate action
which enforced time-based access control per stream. A stream as seen by
this switch is identified by {MAC DA, VID}.
We use the standard forwarding selftest topology with 2 host interfaces
and 2 switch interfaces. The host ports must require timestamping non-IP
packets and supporting tc-etf offload, for isochron to work. The
isochron program monitors network sync status (ptp4l, phc2sys) and
deterministically transmits packets to the switch such that the tc-gate
action either (a) always accepts them based on its schedule, or
(b) always drops them.
I tried to keep as much of the logic that isn't specific to the NXP
LS1028A in a new tsn_lib.sh, for future reuse. This covers
synchronization using ptp4l and phc2sys, and isochron.
The cycle-time chosen for this selftest isn't particularly impressive
(and the focus is the functionality of the switch), but I didn't really
know what to do better, considering that it will mostly be run during
debugging sessions, various kernel bloatware would be enabled, like
lockdep, KASAN, etc, and we certainly can't run any races with those on.
I tried to look through the kselftest framework for other real time
applications and didn't really find any, so I'm not sure how better to
prepare the environment in case we want to go for a lower cycle time.
At the moment, the only thing the selftest is ensuring is that dynamic
frequency scaling is disabled on the CPU that isochron runs on. It would
probably be useful to have a blacklist of kernel config options (checked
through zcat /proc/config.gz) and some cyclictest scripts to run
beforehand, but I saw none of those.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20220501112953.3298973-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
