Wait tx complete (#3165)

* Implement radio transmission drain mechanism and update shared memory structure
* don't wait for timeout if baseband already in shut down state

firmware/application/baseband_api.cpp

@@ -443,6 +443,10 @@ void set_p25tx_data(const uint8_t* dibits, uint16_t frame_length) {
 
 static bool baseband_image_running = false;
 
+bool is_image_running() {
+    return baseband_image_running;
+}
+
 void run_image(const spi_flash::image_tag_t image_tag) {
     if (baseband_image_running) {
         chDbgPanic("BBRunning");

firmware/application/baseband_api.hpp

@@ -125,6 +125,7 @@ void request_rssi_beep();
 void request_beep_stop();
 void request_audio_beep(uint32_t freq, uint32_t sample_rate, uint32_t duration_ms);
 
+bool is_image_running();
 void run_image(const portapack::spi_flash::image_tag_t image_tag);
 void run_prepared_image(const uint32_t m4_code);
 void shutdown();

firmware/application/radio.cpp

@@ -50,7 +50,7 @@ using namespace hackrf::one;
 
 #include "portapack.hpp"
 #include "portapack_persistent_memory.hpp"
-
+#include "baseband_api.hpp"
 #include "hal.h"  // For LPC_SGPIO
 
 #include <array>
@@ -413,6 +413,19 @@ void set_rx_max283x_iq_phase_calibration(const size_t v) {
 }
 
 void disable() {
+    if (direction == rf::Direction::Transmit && baseband::is_image_running()) {
+        static constexpr uint32_t radio_tx_drain_timeout_ms = 100;
+        shared_memory.radio_tx_drain = 1;  // Request drain of the current DMA queue.
+        for (uint32_t waited_ms = 0;
+             shared_memory.radio_tx_drain && (waited_ms < radio_tx_drain_timeout_ms);
+             ++waited_ms) {
+            chThdSleepMilliseconds(1);
+        }
+    }
+    /* Never allow shutdown to block indefinitely waiting for a drain
+     * acknowledgement that may never arrive in normal operation. */
+    shared_memory.radio_tx_drain = 0;
+
     set_antenna_bias(false);
     baseband_codec.set_mode(max5864::Mode::Shutdown);
 #ifdef PRALINE

firmware/baseband/baseband_thread.cpp

@@ -90,7 +90,7 @@ void BasebandThread::run() {
 #ifdef PRALINE
     shared_memory.m4_streaming_marker = 0xAA;  // Phase 0 instrumentation
 #endif
-
+    uint8_t buffer_drained = 0;  // to count how many dma buffers we already emptied
     while (!chThdShouldTerminate()) {
 #ifdef PRALINE
         shared_memory.m4_baseband_loops++;  // Phase 0 instrumentation
@@ -117,11 +117,20 @@ void BasebandThread::run() {
             }
 
             if (baseband_processor_) {
-                baseband_processor_->execute(buffer);
+                if (shared_memory.radio_tx_drain == 0) {  // only generate if not draining.
+                    baseband_processor_->execute(buffer);
+                }
+            }
+            if (shared_memory.radio_tx_drain == 1) {
+                buffer_drained++;
+                if (buffer_drained >= 4) {             // We have 4 buffers, so after draining 4 we should be safe to disable.
+                    shared_memory.radio_tx_drain = 0;  // Clear the drain request to allow normal operation to resume.
+                    buffer_drained = 0;
+                }
             }
         }
     }
-
+    shared_memory.radio_tx_drain = 0;
     i2s::i2s0::tx_mute();
     baseband::dma::disable();
     baseband_sgpio.streaming_disable();

firmware/common/portapack_shared_memory.hpp

@@ -85,7 +85,7 @@ struct SharedMemory {
     uint16_t volatile m4_stack_usage{0};
     uint32_t volatile m4_heap_usage{0};
     uint16_t volatile m4_buffer_missed{0};
-
+    uint8_t volatile radio_tx_drain{0};  // to indicate the baseband thread to drain the tx buffer, and wait for it, before radio::disable()
 #ifdef PRALINE
     // Phase 0 instrumentation counters for PRALINE radio debugging
     uint32_t volatile m4_dma_xfr_count{0};    // DMA transfer_complete() calls