6.1-stable review patch. If anyone has any objections, please let me know.
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From: Felipe Negrelli Wolter felipe.negrelliwolter@silabs.com
[ Upstream commit ea2274ab0b18549dbf0e755e41d8c5e8b5232dc3 ]
When frames are sent over the air, the device always applies the data rates in descending order. The driver assumed Minstrel also provided rate in descending order.
However, in some cases, Minstrel can a choose a fallback rate greater than the primary rate. In this case, the two rates was inverted, the device try highest rate first and we get many retries.
Since the device always applies rates in descending order, the workaround is to drop the rate when it higher than its predecessor in the rate list. Thus [ 4, 5, 3 ] becomes [ 4, 3 ].
This patch has been tested in isolated room with a series of attenuators. Here are the Minstrel statistics with 80dBm of attenuation:
Without the fix:
best ____________rate__________ ____statistics___ _____last____ ______sum-of________ mode guard # rate [name idx airtime max_tp] [avg(tp) avg(prob)] [retry|suc|att] [#success | #attempts] HT20 LGI 1 S MCS0 0 1477 5.6 5.2 82.7 3 0 0 3 4 HT20 LGI 1 MCS1 1 738 10.6 0.0 0.0 0 0 0 0 1 HT20 LGI 1 D MCS2 2 492 14.9 13.5 81.5 5 0 0 5 9 HT20 LGI 1 C MCS3 3 369 18.8 17.6 84.3 5 0 0 76 96 HT20 LGI 1 A P MCS4 4 246 25.4 22.4 79.5 5 0 0 11268 14026 HT20 LGI 1 B S MCS5 5 185 30.7 19.7 57.7 5 8 9 3918 9793 HT20 LGI 1 MCS6 6 164 33.0 0.0 0.0 5 0 0 6 102 HT20 LGI 1 MCS7 7 148 35.1 0.0 0.0 0 0 0 0 44
With the fix:
best ____________rate__________ ____statistics___ _____last____ ______sum-of________ mode guard # rate [name idx airtime max_tp] [avg(tp) avg(prob)] [retry|suc|att] [#success | #attempts] HT20 LGI 1 S MCS0 0 1477 5.6 1.8 28.6 1 0 0 1 5 HT20 LGI 1 DP MCS1 1 738 10.6 9.7 82.6 4 0 0 14 34 HT20 LGI 1 MCS2 2 492 14.9 9.2 55.4 5 0 0 52 77 HT20 LGI 1 B S MCS3 3 369 18.8 15.6 74.9 5 1 1 417 554 HT20 LGI 1 A MCS4 4 246 25.4 16.7 59.2 5 1 1 13812 17951 HT20 LGI 1 C S MCS5 5 185 30.7 14.0 41.0 5 1 5 57 640 HT20 LGI 1 MCS6 6 164 33.0 0.0 0.0 0 0 1 0 48 HT20 LGI 1 S MCS7 7 148 35.1 0.0 0.0 0 0 0 0 36
We can notice the device try now to send with lower rates (and high success rates). At the end, we measured 20-25% better throughput with this patch.
Fixes: 9bca45f3d692 ("staging: wfx: allow to send 802.11 frames") Tested-by: Olivier Souloumiac olivier.souloumiac@silabs.com Tested-by: Alexandr Suslenko suslenko.o@ajax.systems Reported-by: Alexandr Suslenko suslenko.o@ajax.systems Co-developed-by: Jérôme Pouiller jerome.pouiller@silabs.com Signed-off-by: Jérôme Pouiller jerome.pouiller@silabs.com Signed-off-by: Felipe Negrelli Wolter felipe.negrelliwolter@silabs.com Signed-off-by: Kalle Valo kvalo@kernel.org Link: https://lore.kernel.org/r/20231004123039.157112-1-jerome.pouiller@silabs.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireless/silabs/wfx/data_tx.c | 71 +++++++++-------------- 1 file changed, 29 insertions(+), 42 deletions(-)
diff --git a/drivers/net/wireless/silabs/wfx/data_tx.c b/drivers/net/wireless/silabs/wfx/data_tx.c index 6a5e52a96d183..caa22226b01bc 100644 --- a/drivers/net/wireless/silabs/wfx/data_tx.c +++ b/drivers/net/wireless/silabs/wfx/data_tx.c @@ -226,53 +226,40 @@ static u8 wfx_tx_get_link_id(struct wfx_vif *wvif, struct ieee80211_sta *sta,
static void wfx_tx_fixup_rates(struct ieee80211_tx_rate *rates) { - int i; - bool finished; + bool has_rate0 = false; + int i, j;
- /* Firmware is not able to mix rates with different flags */ - for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) { - if (rates[0].flags & IEEE80211_TX_RC_SHORT_GI) - rates[i].flags |= IEEE80211_TX_RC_SHORT_GI; - if (!(rates[0].flags & IEEE80211_TX_RC_SHORT_GI)) + for (i = 1, j = 1; j < IEEE80211_TX_MAX_RATES; j++) { + if (rates[j].idx == -1) + break; + /* The device use the rates in descending order, whatever the request from minstrel. + * We have to trade off here. Most important is to respect the primary rate + * requested by minstrel. So, we drops the entries with rate higher than the + * previous. + */ + if (rates[j].idx >= rates[i - 1].idx) { + rates[i - 1].count += rates[j].count; + rates[i - 1].count = min_t(u16, 15, rates[i - 1].count); + } else { + memcpy(rates + i, rates + j, sizeof(rates[i])); + if (rates[i].idx == 0) + has_rate0 = true; + /* The device apply Short GI only on the first rate */ rates[i].flags &= ~IEEE80211_TX_RC_SHORT_GI; - if (!(rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS)) - rates[i].flags &= ~IEEE80211_TX_RC_USE_RTS_CTS; - } - - /* Sort rates and remove duplicates */ - do { - finished = true; - for (i = 0; i < IEEE80211_TX_MAX_RATES - 1; i++) { - if (rates[i + 1].idx == rates[i].idx && - rates[i].idx != -1) { - rates[i].count += rates[i + 1].count; - if (rates[i].count > 15) - rates[i].count = 15; - rates[i + 1].idx = -1; - rates[i + 1].count = 0; - - finished = false; - } - if (rates[i + 1].idx > rates[i].idx) { - swap(rates[i + 1], rates[i]); - finished = false; - } + i++; } - } while (!finished); + } /* Ensure that MCS0 or 1Mbps is present at the end of the retry list */ - for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) { - if (rates[i].idx == 0) - break; - if (rates[i].idx == -1) { - rates[i].idx = 0; - rates[i].count = 8; /* == hw->max_rate_tries */ - rates[i].flags = rates[i - 1].flags & IEEE80211_TX_RC_MCS; - break; - } + if (!has_rate0 && i < IEEE80211_TX_MAX_RATES) { + rates[i].idx = 0; + rates[i].count = 8; /* == hw->max_rate_tries */ + rates[i].flags = rates[0].flags & IEEE80211_TX_RC_MCS; + i++; + } + for (; i < IEEE80211_TX_MAX_RATES; i++) { + memset(rates + i, 0, sizeof(rates[i])); + rates[i].idx = -1; } - /* All retries use long GI */ - for (i = 1; i < IEEE80211_TX_MAX_RATES; i++) - rates[i].flags &= ~IEEE80211_TX_RC_SHORT_GI; }
static u8 wfx_tx_get_retry_policy_id(struct wfx_vif *wvif, struct ieee80211_tx_info *tx_info)