mt76: Fix DTS power-limits on little endian systems

The power-limits for ru and mcs and stored in the devicetree as bytewise
array (often with sizes which are not a multiple of 4). These arrays have a
prefix which defines for how many modes a line is applied. This prefix is
also only a byte - but the code still tried to fix the endianness of this
byte with a be32 operation. As result, loading was mostly failing or was
sending completely unexpected values to the firmware.

Since the other rates are also stored in the devicetree as bytewise arrays,
just drop the u32 access + be32_to_cpu conversion and directly access them
as bytes arrays.

Signed-off-by: Sven Eckelmann (Plasma Cloud) <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20152
Signed-off-by: Hauke Mehrtens <[email protected]>

diff --git a/package/kernel/mt76/patches/0001-wifi-mt76-Fix-DTS-power-limits-on-little-endian-syst.patch b/package/kernel/mt76/patches/0001-wifi-mt76-Fix-DTS-power-limits-on-little-endian-syst.patch
new file mode 100644 (file)
index 0000000..bd21a23
--- /dev/null
+++ b/package/kernel/mt76/patches/0001-wifi-mt76-Fix-DTS-power-limits-on-little-endian-syst.patch
@@ -0,0 +1,125 @@
+From: Sven Eckelmann (Plasma Cloud) <[email protected]>
+Date: Mon, 30 Jun 2025 16:18:21 +0200
+Subject: wifi: mt76: Fix DTS power-limits on little endian systems
+
+The power-limits for ru and mcs and stored in the devicetree as bytewise
+array (often with sizes which are not a multiple of 4). These arrays have a
+prefix which defines for how many modes a line is applied. This prefix is
+also only a byte - but the code still tried to fix the endianness of this
+byte with a be32 operation. As result, loading was mostly failing or was
+sending completely unexpected values to the firmware.
+
+Since the other rates are also stored in the devicetree as bytewise arrays,
+just drop the u32 access + be32_to_cpu conversion and directly access them
+as bytes arrays.
+
+Cc: [email protected]
+Fixes: 22b980badc0f ("mt76: add functions for parsing rate power limits from DT")
+Fixes: a9627d992b5e ("mt76: extend DT rate power limits to support 11ax devices")
+Signed-off-by: Sven Eckelmann (Plasma Cloud) <[email protected]>
+Forwarded: https://lore.kernel.org/r/[email protected]
+
+--- a/eeprom.c
++++ b/eeprom.c
+@@ -273,6 +273,19 @@ mt76_get_of_array(struct device_node *np
+       return prop->value;
+ }
+ 
++static const s8 *
++mt76_get_of_array_s8(struct device_node *np, char *name, size_t *len, int min)
++{
++      struct property *prop = of_find_property(np, name, NULL);
++
++      if (!prop || !prop->value || prop->length < min)
++              return NULL;
++
++      *len = prop->length;
++
++      return prop->value;
++}
++
+ struct device_node *
+ mt76_find_channel_node(struct device_node *np, struct ieee80211_channel *chan)
+ {
+@@ -314,7 +327,7 @@ mt76_get_txs_delta(struct device_node *n
+ }
+ 
+ static void
+-mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const __be32 *data,
++mt76_apply_array_limit(s8 *pwr, size_t pwr_len, const s8 *data,
+                      s8 target_power, s8 nss_delta, s8 *max_power)
+ {
+       int i;
+@@ -323,15 +336,14 @@ mt76_apply_array_limit(s8 *pwr, size_t p
+               return;
+ 
+       for (i = 0; i < pwr_len; i++) {
+-              pwr[i] = min_t(s8, target_power,
+-                             be32_to_cpu(data[i]) + nss_delta);
++              pwr[i] = min_t(s8, target_power, data[i] + nss_delta);
+               *max_power = max(*max_power, pwr[i]);
+       }
+ }
+ 
+ static void
+ mt76_apply_multi_array_limit(s8 *pwr, size_t pwr_len, s8 pwr_num,
+-                           const __be32 *data, size_t len, s8 target_power,
++                           const s8 *data, size_t len, s8 target_power,
+                            s8 nss_delta, s8 *max_power)
+ {
+       int i, cur;
+@@ -339,8 +351,7 @@ mt76_apply_multi_array_limit(s8 *pwr, si
+       if (!data)
+               return;
+ 
+-      len /= 4;
+-      cur = be32_to_cpu(data[0]);
++      cur = data[0];
+       for (i = 0; i < pwr_num; i++) {
+               if (len < pwr_len + 1)
+                       break;
+@@ -355,7 +366,7 @@ mt76_apply_multi_array_limit(s8 *pwr, si
+               if (!len)
+                       break;
+ 
+-              cur = be32_to_cpu(data[0]);
++              cur = data[0];
+       }
+ }
+ 
+@@ -366,7 +377,7 @@ s8 mt76_get_rate_power_limits(struct mt7
+ {
+       struct mt76_dev *dev = phy->dev;
+       struct device_node *np;
+-      const __be32 *val;
++      const s8 *val;
+       char name[16];
+       u32 mcs_rates = dev->drv->mcs_rates;
+       u32 ru_rates = ARRAY_SIZE(dest->ru[0]);
+@@ -412,21 +423,21 @@ s8 mt76_get_rate_power_limits(struct mt7
+ 
+       txs_delta = mt76_get_txs_delta(np, hweight16(phy->chainmask));
+ 
+-      val = mt76_get_of_array(np, "rates-cck", &len, ARRAY_SIZE(dest->cck));
++      val = mt76_get_of_array_s8(np, "rates-cck", &len, ARRAY_SIZE(dest->cck));
+       mt76_apply_array_limit(dest->cck, ARRAY_SIZE(dest->cck), val,
+                              target_power, txs_delta, &max_power);
+ 
+-      val = mt76_get_of_array(np, "rates-ofdm",
+-                              &len, ARRAY_SIZE(dest->ofdm));
++      val = mt76_get_of_array_s8(np, "rates-ofdm",
++                                 &len, ARRAY_SIZE(dest->ofdm));
+       mt76_apply_array_limit(dest->ofdm, ARRAY_SIZE(dest->ofdm), val,
+                              target_power, txs_delta, &max_power);
+ 
+-      val = mt76_get_of_array(np, "rates-mcs", &len, mcs_rates + 1);
++      val = mt76_get_of_array_s8(np, "rates-mcs", &len, mcs_rates + 1);
+       mt76_apply_multi_array_limit(dest->mcs[0], ARRAY_SIZE(dest->mcs[0]),
+                                    ARRAY_SIZE(dest->mcs), val, len,
+                                    target_power, txs_delta, &max_power);
+ 
+-      val = mt76_get_of_array(np, "rates-ru", &len, ru_rates + 1);
++      val = mt76_get_of_array_s8(np, "rates-ru", &len, ru_rates + 1);
+       mt76_apply_multi_array_limit(dest->ru[0], ARRAY_SIZE(dest->ru[0]),
+                                    ARRAY_SIZE(dest->ru), val, len,
+                                    target_power, txs_delta, &max_power);