Jaguar1/2/3: unified tx_retry knob (DEVOURER_TX_RETRY_LIMIT, default 0)

All three Jaguar generations hardcoded a per-frame TX retry limit of 12
(jaguar1: SET_TX_DESC_DATA_RETRY_LIMIT, jaguar2/3:
RTS_DATA_RTY_LMT in the fill_data_tx_desc builders). On a busy
half-duplex link the chip retried each frame up to 12x on collision,
flooding the air and blinding the receiver — consecutive video fragments
lost, downlink FEC cannot repair.

Now every chip honors cfg.tx.retry_limit (env DEVOURER_TX_RETRY_LIMIT),
applied per frame with tx_desc re-checksum; the A-MPDU path uses it too.
Default 0 restores the pre-regression behaviour (verified: 0 losses with
alink enabled on 8812AU).

Author: vertexodessa

examples/common/env_config.cpp

@@ -106,6 +106,8 @@ devourer::DeviceConfig devourer_config_from_env() {
     if (devourer::parse_ampdu_mode(e, m))
       cfg.tx.ampdu = m;
   }
+  if (env_long("DEVOURER_TX_RETRY_LIMIT", &v))
+    cfg.tx.retry_limit = static_cast<int>(v < 0 ? 0 : (v > 63 ? 63 : v));
 
   /* ---- bf ---- */
   if (const char *snd = env_str("DEVOURER_BF_ARM_SOUNDER")) {

src/DeviceConfig.h

@@ -175,6 +175,12 @@ struct DeviceConfig {
      * Runtime equivalent: StartCwTone/StopCwTone on the concrete device. */
     bool cw_tone = false;
     uint8_t cw_tone_gain = 0;
+    /* env: DEVOURER_TX_RETRY_LIMIT — per-frame hardware retry limit (0..63).
+     * Maps to the TX descriptor DATA_RETRY_LIMIT / RTS_DATA_RTY_LMT field
+     * (Dword4 bits 18-23). 0 = no retries (WFB default: FEC provides
+     * reliability, not MAC retries). On a busy half-duplex link retries flood
+     * the air and blind the receiver. */
+    int retry_limit = 0;
     /* env: DEVOURER_TX_USB_AGG — USB TX aggregation: max frames packed into
      * one bulk-OUT URB by send_packets (0 = off, the default: send_packets
      * degrades to a per-frame loop and every TX path is byte-identical to

src/jaguar1/RtlJaguarDevice.cpp

@@ -1171,8 +1171,10 @@ size_t RtlJaguarDevice::build_tx_block(const uint8_t *packet, size_t length,
   SET_TX_DESC_RETRY_LIMIT_ENABLE_8812(usb_frame, 1);
   if (!is_8814a) {
     /* 88XXau leaves DATA_RETRY_LIMIT=0 for monitor injection on 8814A
-     * (RETRY_LIMIT_ENABLE stays set to 1 in both). */
-    SET_TX_DESC_DATA_RETRY_LIMIT_8812(usb_frame, 12);
+     * (RETRY_LIMIT_ENABLE stays set to 1 in both).
+     * Use cfg.tx.retry_limit (DEVOURER_TX_RETRY_LIMIT, default 0) instead of
+     * the hardcoded 12 — retries flood the air on a busy half-duplex link. */
+    SET_TX_DESC_DATA_RETRY_LIMIT_8812(usb_frame, _cfg.tx.retry_limit);
   }
   if (sgi) {
     _logger->info("short gi enabled,set sgi");
@@ -1228,7 +1230,7 @@ size_t RtlJaguarDevice::build_tx_block(const uint8_t *packet, size_t length,
       SET_TX_DESC_AGG_ENABLE_8812(usb_frame, 1);
       SET_TX_DESC_MAX_AGG_NUM_8812(usb_frame, am.max_num & 0x1f);
       SET_TX_DESC_AMPDU_DENSITY_8812(usb_frame, am.density & 0x7);
-      SET_TX_DESC_DATA_RETRY_LIMIT_8812(usb_frame, am.no_ack ? 0 : 12);
+      SET_TX_DESC_DATA_RETRY_LIMIT_8812(usb_frame, am.no_ack ? 0 : _cfg.tx.retry_limit);
     }
     if (_cfg.debug.tx_qsel)
       SET_TX_DESC_QUEUE_SEL_8812(usb_frame, *_cfg.debug.tx_qsel);

src/jaguar2/RtlJaguar2Device.cpp

@@ -1529,6 +1529,12 @@ size_t RtlJaguar2Device::build_tx_block(const uint8_t *packet, size_t length,
     SET_TX_DESC_SW_DEFINE_8822B(out, _tx_rpt_tag.fetch_add(1) & 0xff);
     jaguar2::cal_txdesc_chksum_8822b(out);
   }
+  /* Per-frame retry limit from cfg (DEVOURER_TX_RETRY_LIMIT, default 0) —
+   * the fill_data_tx_desc builder hardcodes 12, which floods a busy
+   * half-duplex link. Both fields sit inside the checksummed span. */
+  SET_TX_DESC_RTY_LMT_EN_8822B(out, 1);
+  SET_TX_DESC_RTS_DATA_RTY_LMT_8822B(out, _cfg.tx.retry_limit);
+  jaguar2::cal_txdesc_chksum_8822b(out);
   const devourer::AmpduMode am = _ampdu; /* one lock-free load */
   if (am.enabled || _cfg.debug.tx_qsel || _cfg.debug.tx_ampdu_max) {
     /* A-MPDU descriptor half. The product SetAmpduMode state applies first
@@ -1541,7 +1547,7 @@ size_t RtlJaguar2Device::build_tx_block(const uint8_t *packet, size_t length,
       SET_TX_DESC_AGG_EN_8822B(out, 1);
       SET_TX_DESC_MAX_AGG_NUM_8822B(out, am.max_num & 0x1f);
       SET_TX_DESC_AMPDU_DENSITY_8822B(out, am.density & 0x7);
-      SET_TX_DESC_RTS_DATA_RTY_LMT_8822B(out, am.no_ack ? 0 : 12);
+      SET_TX_DESC_RTS_DATA_RTY_LMT_8822B(out, am.no_ack ? 0 : _cfg.tx.retry_limit);
     }
     if (_cfg.debug.tx_qsel)
       SET_TX_DESC_QSEL_8822B(out, *_cfg.debug.tx_qsel);

src/jaguar3/RtlJaguar3Device.cpp

@@ -2006,6 +2006,12 @@ size_t RtlJaguar3Device::build_tx_block(const uint8_t *packet, size_t length,
     SET_TX_DESC_SW_DEFINE_8822C(out, _tx_rpt_tag.fetch_add(1) & 0xff);
     jaguar3::cal_txdesc_chksum_8822c(out);
   }
+  /* Per-frame retry limit from cfg (DEVOURER_TX_RETRY_LIMIT, default 0) —
+   * the fill_data_tx_desc builder hardcodes 12, which floods a busy
+   * half-duplex link. Both fields sit inside the checksummed span. */
+  SET_TX_DESC_RTY_LMT_EN_8822C(out, 1);
+  SET_TX_DESC_RTS_DATA_RTY_LMT_8822C(out, _cfg.tx.retry_limit);
+  jaguar3::cal_txdesc_chksum_8822c(out);
   const devourer::AmpduMode am = _ampdu; /* one lock-free load */
   if (am.enabled || _cfg.debug.tx_qsel || _cfg.debug.tx_ampdu_max) {
     /* A-MPDU descriptor half. The product SetAmpduMode state applies first,
@@ -2017,7 +2023,7 @@ size_t RtlJaguar3Device::build_tx_block(const uint8_t *packet, size_t length,
       SET_TX_DESC_AGG_EN_8822C(out, 1);
       SET_TX_DESC_MAX_AGG_NUM_8822C(out, am.max_num & 0x1f);
       SET_TX_DESC_AMPDU_DENSITY_8822C(out, am.density & 0x7);
-      SET_TX_DESC_RTS_DATA_RTY_LMT_8822C(out, am.no_ack ? 0 : 12);
+      SET_TX_DESC_RTS_DATA_RTY_LMT_8822C(out, am.no_ack ? 0 : _cfg.tx.retry_limit);
     }
     if (_cfg.debug.tx_qsel)
       SET_TX_DESC_QSEL_8822C(out, *_cfg.debug.tx_qsel);