From 45f53d98cbaa078907b6a300ff3974dfb5ae8776 Mon Sep 17 00:00:00 2001 From: Junjie Cao Date: Thu, 10 Sep 2026 09:23:00 +0800 Subject: [PATCH] wifi: mt76: mt792x: treat 0xff ACPI SAR entries as no limit Some ASUS firmware carries 0xff in MTGS power slots. The driver narrows the byte to s8, so the slot reads as -1 in its 0.5 dBm units, wins the min() against the regulatory limit and caps every rate the driver programs. On an ASUS Zenbook 14 UM3406HA (MT7922) all six MTGS tables hold 0xff in every power byte, and txpower_sku shows tmac 3 on every supported OFDM/HT/VHT/HE rate against EEPROM entries of 25-39, under both the FR and the world regulatory domain. Huy Nguyen Dinh Quang saw the same clamp on a Vivobook S 14 M5406WA, with 5 GHz TX at ~40 Mbps, and proposed skipping the geo entry. Skip a geo entry whose power byte is 0xff. The MTDS entry is narrowed the same way on its way into the geo lookup, so give it the same treatment, and clamp the dynamic value plus offset at 127 so a no-limit entry cannot wrap. Fixes: f965333e491e ("mt76: mt7921: introduce ACPI SAR support") Link: https://bugzilla.redhat.com/show_bug.cgi?id=2515420 Reported-by: Huy Nguyen Dinh Quang Closes: https://lore.kernel.org/linux-wireless/20260827134820.2607530-1-huynguyendinhquang@gmail.com/ Signed-off-by: Junjie Cao Tested-by: Cristian Fleischer Link: https://patch.msgid.link/acb947435fc78d5c06039c7bd5609c735468b0ee.1789002236.git.junjie.cao@intel.com Signed-off-by: Felix Fietkau --- .../wireless/mediatek/mt76/mt792x_acpi_sar.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c b/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c index b468051fbe68..0ffb277f9909 100644 --- a/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c +++ b/drivers/net/wireless/mediatek/mt76/mt792x_acpi_sar.c @@ -279,10 +279,18 @@ mt792x_asar_get_geo_pwr(struct mt792x_phy *phy, if (idx >= max) return dyn_power; - geo_power = (band_pwr + idx)->pwr; - dyn_power += (band_pwr + idx)->offset; + band_pwr += idx; - return min(geo_power, dyn_power); + /* Some OEM tables carry 0xff here; narrowed to s8 that is -1 and + * wins the min() below. Take it as no limit. + */ + if (band_pwr->pwr == 0xff) + return dyn_power; + + geo_power = band_pwr->pwr; + + return min_t(int, geo_power, + min_t(int, dyn_power + band_pwr->offset, 127)); } static s8 @@ -315,7 +323,9 @@ mt792x_asar_range_pwr(struct mt792x_phy *phy, else band = NL80211_BAND_2GHZ; - return mt792x_asar_get_geo_pwr(phy, band, limit[idx]); + /* 0xff: no dynamic limit, see mt792x_asar_get_geo_pwr() */ + return mt792x_asar_get_geo_pwr(phy, band, + limit[idx] == 0xff ? 127 : limit[idx]); } int mt792x_init_acpi_sar_power(struct mt792x_phy *phy, bool set_default)