Enable configurable dfs_pri_multiplier. The ETSI typ2 type3 radar
detection ratio is lower than expected(>80%) while channel loading is
high(>30%). The host improvement for this are:
1. Add configurable dfs_pri_multiplier, controlled by
DFS_PRI_MULTIPLIER. Default value 2, min 1, max 10.
2. Lower adrastea ETSI type 2/3/4 radar filter rssi_threshold,
controlled by DFS_OVERRIDE_RF_THRESHOLD, dfs log shows that
QCS405 target report RSSI range [18, 45] while radar power
is 3 dbm. By using default rssi_threshold 24 will reject
many radar pulses, which leads to low detection ratio.
3. Calculate deltapri for each searchpri based on dfs_pri_multiplier
in dfs_count_the_other_delay_elements(), check deltapri
between [1, dfs_pri_multiplier] * refpri and searchpri, if
the primargin is desired, mark it as matched pulse.
4. Pick lowpri as refpri for the radar filter with
rf_ignore_pri_window equals to 0 while DFS_PRI_MULTIPLIER is
enabled. Observed original findref logic has some problems
which selects refpri is bigger than lowpri, which leads to
the lowpri pulses pri_match are set to 0, and in this case,
radar was not detected. Example for the issue, assume
rf->rf_pulseid 34 (ETSI type 2) has 7 pulses with pri:
1489, 2978, 2978, 2978, 1489, 2978, 1489 us in this case,
highscore is 4 (2978), scoreindex is 5, refpri is 2978, which
leads to: index 0, 4, 6 pulses with pri_match 0 in
dfs_count_the_other_delay_elements(). The fix is to select
lowpri as refpri(1489 in this case).
Change-Id: I1f3ca3298c9ab1f1e2651ad6b4a0a4810f83f8a1
CRs-Fixed: 2522506
9a28ed0437