tree 4a325236022e085befde949db834e76cb3766745
parent 5a8540f9c1052ae4d4f8df037af19be2fd302e0c
author Pau Espin Pedrol <pespin@sysmocom.de> 1614952678 +0100
committer pespin <pespin@sysmocom.de> 1615549482 +0000

pcu: transmit PCUIF DATA.ind with len=0 when no UL data to transmit

PCUIF will be updated to always send DATA.ind for each expected block FN
on any activated PDCH slot, irrespective of whether valid data was
received or not, similarly to what's done already for TRXDv1 NOPE.ind in
TRXD and TCH channels in OsmoBTS. The aim at this change is to be able to
track TDMA clock in an accurate way without hops, and hence be able to
detect on time whether expected UL blocks (SF, RRBP poll) didn't arrive.

Older osmo-pcu versions can cope well with this change, they will simply
print an error upon ach data_len=0 messages received and submit a GSMTAP
block, then discard it, so tests still pass.
Nevertheless, a new module parameter is added to disable this new
behavior in order to avoid logs and pcap files ending up clogged with
uneeded information until a new osmo-pcu release appears.

Related: OS#5020
Change-Id: Ib4f97a9bcfa68230945effeb6412218faa64ec78