diff options
| -rw-r--r-- | drivers/staging/cw1200/txrx.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/drivers/staging/cw1200/txrx.c b/drivers/staging/cw1200/txrx.c index b8859326612..1a48689660c 100644 --- a/drivers/staging/cw1200/txrx.c +++ b/drivers/staging/cw1200/txrx.c @@ -127,6 +127,59 @@ static void tx_policy_build(const struct cw1200_common *priv, limit -= rates[i].count; } } + + /* HACK!!! Device has problems (at least) switching from + * 54Mbps CTS to 1Mbps. This switch takes enormous amount + * of time (100-200 ms), leading to valuable throughput drop. + * As a workaround, additional g-rates are injected to the + * policy. + */ + if (count == 2 && !(rates[0].flags & IEEE80211_TX_RC_MCS) && + rates[0].idx > 4 && rates[0].count > 2 && + rates[1].idx < 2) { + /* ">> 1" is an equivalent of "/ 2", but faster */ + int mid_rate = (rates[0].idx + 4) >> 1; + + /* Decrease number of retries for the initial rate */ + rates[0].count -= 2; + + if (mid_rate != 4) { + /* Keep fallback rate at 1Mbps. */ + rates[3] = rates[1]; + + /* Inject 1 transmission on lowest g-rate */ + rates[2].idx = 4; + rates[2].count = 1; + rates[2].flags = rates[1].flags; + + /* Inject 1 transmission on mid-rate */ + rates[1].idx = mid_rate; + rates[1].count = 1; + + /* Fallback to 1 Mbps is a really bad thing, + * so let's try to increase probability of + * successful transmission on the lowest g rate + * even more */ + if (rates[0].count >= 3) { + --rates[0].count; + ++rates[2].count; + } + + /* Adjust amount of rates defined */ + count += 2; + } else { + /* Keep fallback rate at 1Mbps. */ + rates[2] = rates[1]; + + /* Inject 2 transmissions on lowest g-rate */ + rates[1].idx = 4; + rates[1].count = 2; + + /* Adjust amount of rates defined */ + count += 1; + } + } + policy->defined = cw1200_get_tx_rate(priv, &rates[0])->hw_value + 1; for (i = 0; i < count; ++i) { |