Re: [PATCH] ath9k: fix per-packet TX-power cap for TPC

["Toke Høiland-Jørgensen" <toke@kernel.org>]

Jonas Jelonek <jelonek.jonas@gmail.com> writes:

> Fix incorrect usage of plain rate_idx as index into the max (power) per
> rate lookup table.
>
> For transmit power control (TPC), the ath9k driver maintains internal
> tables (in struct ath_hw) to store the max allowed power level per rate.
> They are used to limit a given TX-power according to regulatory and user
> limits in the TX-path per packet. The tables are filled in a predefined
> order, starting with values for CCK + OFDM rates and followed by the
> values for MCS rates. Thus, the maximum power levels for MCS do not
> start at index 0 in the table but are shifted by a fixed value.
>
> The TX-power limiting in ath_get_rate_txpower did not apply this shift,
> thus retrieved the incorrect maximum power level. For example, the
> maximum power for OFDM rate 0 was used for MCS rate 0. If STBC was used,
> the power was mostly limited to 0 because the STBC table is zeroed for
> legacy CCK/OFDM rates. This patch fixes this table lookup.
>
> Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>

So what effect does this bug have in practice? Also, how did you test
the patch? :)

-Toke