Hi,

Vladimir Oltean [off-list ref] writes:

Hi Murali,

On Wed, 22 Jan 2020 at 20:04, Murali Karicheri [off-list ref] wrote:

quoted

I have question about the below parameters in The Gate Parameter Table
that are not currently supported by tc command. Looks like they need to
be shown to user for management.

     - ConfigChange - Looks like this needs to be controlled by
       user. After sending admin command, user send this trigger to start
       copying admin schedule to operation schedule. Is this getting
       added to tc command?

"The ConfigChange parameter signals the start of a
configuration change for the gate
when it is set to TRUE. This should only be done
when the various administrative parameters
are all set to appropriate values."

As far as my understanding goes, all tc-taprio commands currently
behave as though this boolean is implicitly set to TRUE after the
structures have been set up. I'm not sure there is any value in doing
otherwise.

quoted

     - ConfigChangeTime - The time at which the administrative variables
       that determine the cycle are to be copied across to the
       corresponding operational variables, expressed as a PTP timescale

This is the base-time of the admin schedule, no?

"The PTPtime at which the next config change is scheduled to occur.
The value is a representation of a PTPtime value,
consisting of a 48-bit integer
number of seconds and a 32-bit integer number of nanoseconds."

quoted

     - TickGranularity - the management parameters specified in Gate
       Parameter Table allow a management station to discover the
       characteristics of an implementation’s cycle timer clock
       (TickGranularity) and to set the parameters for the gating cycle
       accordingly.

Not sure who is going to use this and for what purpose, but ok.

quoted

     - ConfigPending - A Boolean variable, set TRUE to indicate that
       there is a new cycle configuration awaiting installation.

I had tried to export something like this (driver calls back into
sch_taprio.c when hw has applied the config, this would result in
ConfigPending = FALSE), but ultimately didn't finish the idea, and it
caused some problems too, due to incorrect RCU usage.

If this should be exported, this should be done from taprio, perhaps
adding a new field to what is exported via the dump() callback, which
should be quite easy.

quoted

     - ConfigChangeError - Error in configuration (AdminBaseTime <
       CurrentTime)

This can be exported similarly.

In my view, having this as a "runtime" error is not useful, as we can
verify this at configuration time.

quoted

     - SupportedListMax - Maximum supported Admin/Open shed list.

Is there a plan to export these from driver through tc show or such
command? The reason being, there would be applications developed to
manage configuration/schedule of TSN nodes that would requires these
information from the node. So would need a support either in tc or
some other means to retrieve them from hardware or driver. That is my
understanding...

Hm, now I understamd what you meant here...

Not sure what answer you expect to receive for "is there any plan".
You can go ahead and propose something, as long as it is reasonably
useful to have.

... if this is indeed useful, perhaps one way to do is to add a subcommand
to TC_SETUP_QDISC_TAPRIO, so we can retrieve the stats/information we want
from the driver. Similar to what cls_flower does.

quoted

Regards,

Murali

--
Murali Karicheri
Texas Instruments

Thanks,
-Vladimir

Cheers,
--
Vinicius