ath: dfs_pri_detector: Demote zero/half completed kernel-doc headers

There are only a couple of these and none of them are conformant.

Fixes the following W=1 kernel build warning(s):

drivers/net/wireless/ath/dfs_pri_detector.c:39: warning: Function parameter or member 'head' not described in 'pulse_elem'
drivers/net/wireless/ath/dfs_pri_detector.c:46: warning: Function parameter or member 'val' not described in 'pde_get_multiple'
drivers/net/wireless/ath/dfs_pri_detector.c:46: warning: Function parameter or member 'fraction' not described in 'pde_get_multiple'
drivers/net/wireless/ath/dfs_pri_detector.c:46: warning: Function parameter or member 'tolerance' not described in 'pde_get_multiple'

Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201102112410.1049272-23-lee.jones@linaro.org

ath: use PRI value given by spec for fixed PRI

PRI value is used as divider when DFS detector analyzes candidate
radar pulses.
If PRI deviation is big from its origin PRI, DFS detector could miss
valid radar reports since HW often misses detecting radar pulses and
causes long interval value of pulses.

For instance from practical results, if runtime PRI is calculated as
1431 for fixed PRI value of 1428 and delta timestamp logs 15719,
the modular remainder will be 1409 and the delta between the remainder
and runtime PRI is 22 that is bigger than PRI tolerance which is 16.
As a result this radar report will be ignored even though it's valid.

By using spec defined PRI for fixed PRI, we can correct this error.

Signed-off-by: Peter Oh <poh@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

ath: DFS - limit number of potential PRI sequences

In the PRI detector, after the current radar pulse
has been checked agains existing PRI sequences, it
is considered as part of a new potential sequence.

Previously, the condition to accept a new sequence
was to have at least the same number of pulses as
the longest matching sequence. This was wrong,
since it led to duplicates of PRI sequences.

This patch changes the acceptance criteria for new
potential sequences from 'at least' to 'more than'
the longest existing.

Detection performance remains unaffected, while
the number of PRI sequences accounted at runtime
(and with it CPU load) is reduced by up to 50%.

Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

ath: enhance radar detection by looking up chirp

Certain radar types such as FCC radar type 5 are using chirp
in their pulses, hence looking up the chirp status will enhance
to avoid false radar detection.

Signed-off-by: Peter Oh <poh@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

ath9k/ath: move dfs pattern detector to ath

Move the DFS pattern detector code to the ath module so
the other Atheros drivers can make us of it. This makes
no functional changes.

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Reviewed-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>