[components] Drop stale UART receive bytes with discard_available (#21030)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

esphome/components/bl0906/bl0906.cpp

@@ -134,9 +134,7 @@ void BL0906::handle_actions_() {
     }
   }
 
-  while (this->available()) {
-    this->read();
-  }
+  this->discard_available();
 
   this->action_queue_.clear();
 }

esphome/components/cm1106/cm1106.cpp

@@ -115,9 +115,7 @@ bool CM1106Component::send_command_expect_ack_(const uint8_t *command, size_t co
 
 bool CM1106Component::cm1106_write_command_(const uint8_t *command, size_t command_len, uint8_t *response,
                                             size_t response_len) {
-  // Empty RX Buffer
-  while (this->available())
-    this->read();
+  this->discard_available();
   this->write_array(command, command_len - 1);
   this->write_byte(cm1106_checksum(command, command_len));
   this->flush();

esphome/components/cse7761/cse7761.cpp

@@ -116,9 +116,7 @@ void CSE7761Component::write_(uint8_t reg, uint16_t data) {
 }
 
 bool CSE7761Component::read_once_(uint8_t reg, uint8_t size, uint32_t *value) {
-  while (this->available()) {
-    this->read();
-  }
+  this->discard_available();
 
   this->write_(reg, 0);
 

esphome/components/dfrobot_sen0465_uart/dfrobot_sen0465_uart.cpp

@@ -40,11 +40,7 @@ void DFRobotSEN0465UARTComponent::loop() {
 
 bool DFRobotSEN0465UARTComponent::write_frame(const uint8_t *frame) {
   // Drop anything left over, such as the answer to the mode change or readings sent before passive mode was set
-  uint8_t byte;
-  while (this->available() > 0) {
-    if (!this->read_byte(&byte))
-      break;
-  }
+  this->discard_available();
   this->rx_count_ = 0;
   this->write_array(frame, FRAME_SIZE);
   return true;

esphome/components/dlms_meter/dlms_meter.cpp

@@ -73,7 +73,7 @@ DlmsMeterComponent::DlmsMeterComponent(const uint32_t receive_timeout_ms, const
   }
 }
 
-void DlmsMeterComponent::setup() { this->flush_rx_buffer_(); }
+void DlmsMeterComponent::setup() { this->discard_available(); }
 
 void DlmsMeterComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "DLMS Meter:");
@@ -122,12 +122,6 @@ void DlmsMeterComponent::loop() {
   }
 }
 
-void DlmsMeterComponent::flush_rx_buffer_() {
-  while (this->available()) {
-    this->read();
-  }
-}
-
 void DlmsMeterComponent::read_rx_buffer_() {
   int available = this->available();
   if (available == 0)
@@ -137,7 +131,7 @@ void DlmsMeterComponent::read_rx_buffer_() {
     ESP_LOGW(TAG, "RX Buffer overflow. Frame too large! Dropping frame.");
     this->bytes_accumulated_ = 0;
 
-    this->flush_rx_buffer_();
+    this->discard_available();
     return;
   }
 
@@ -145,7 +139,7 @@ void DlmsMeterComponent::read_rx_buffer_() {
   if (!success) {
     ESP_LOGW(TAG, "UART read failed. Dropping frame.");
     this->bytes_accumulated_ = 0;
-    this->flush_rx_buffer_();
+    this->discard_available();
     return;
   }
 

esphome/components/dlms_meter/dlms_meter.h

@@ -104,7 +104,6 @@ class DlmsMeterComponent final : public Component, public uart::UARTDevice {
 
  protected:
   void read_rx_buffer_();
-  void flush_rx_buffer_();
   void process_frame_();
   void on_data_(const dlms_parser::AxdrCapture &capture);
 

esphome/components/fingerprint_grow/fingerprint_grow.cpp

@@ -362,8 +362,7 @@ void FingerprintGrowComponent::aura_led_control(uint8_t state, uint8_t speed, ui
 }
 
 uint8_t FingerprintGrowComponent::transfer_(std::vector<uint8_t> &data_buffer) {
-  while (this->available())
-    this->read();
+  this->discard_available();
   this->write((uint8_t) (START_CODE >> 8));
   this->write((uint8_t) (START_CODE & 0xFF));
   this->write(this->address_[0]);

esphome/components/hc8/hc8.cpp

@@ -18,9 +18,7 @@ void HC8Component::setup() {
   this->write_array(HC8_COMMAND_GET_PPM);
   this->flush();
 
-  // ensure the buffer is empty
-  while (this->available())
-    this->read();
+  this->discard_available();
 }
 
 void HC8Component::update() {
@@ -36,8 +34,7 @@ void HC8Component::update() {
     this->status_clear_warning();
   }
 
-  while (this->available())
-    this->read();
+  this->discard_available();
 
   this->write_array(HC8_COMMAND_GET_PPM);
   this->flush();

esphome/components/hlk_fm22x/hlk_fm22x.cpp

@@ -11,9 +11,7 @@ static constexpr uint32_t PAYLOAD_TIMEOUT_MS = 20;
 void HlkFm22xComponent::setup() {
   ESP_LOGCONFIG(TAG, "Setting up HLK-FM22X...");
   this->set_enrolling_(false);
-  while (this->available() > 0) {
-    this->read();
-  }
+  this->discard_available();
   this->defer([this]() { this->send_command_(HlkFm22xCommand::GET_STATUS); });
 }
 
@@ -85,8 +83,7 @@ void HlkFm22xComponent::send_command_(HlkFm22xCommand command, const uint8_t *da
   }
   this->wait_cycles_ = 0;
   this->active_command_ = command;
-  while (this->available() > 0)
-    this->read();
+  this->discard_available();
   this->write((uint8_t) (START_CODE >> 8));
   this->write((uint8_t) (START_CODE & 0xFF));
   this->write((uint8_t) command);
@@ -141,9 +138,7 @@ void HlkFm22xComponent::recv_command_() {
     if (millis() - start > PAYLOAD_TIMEOUT_MS) {
       ESP_LOGE(TAG, "Timeout waiting for payload (%u bytes)", length);
       // Drain any partial payload bytes to resync the parser
-      while (this->available() > 0) {
-        this->read();
-      }
+      this->discard_available();
       return;
     }
     delay(1);

esphome/components/hydreon_rgxx/hydreon_rgxx.cpp

@@ -38,9 +38,7 @@ void HydreonRGxxComponent::dump_config() {
 }
 
 void HydreonRGxxComponent::setup() {
-  while (this->available() != 0) {
-    this->read();
-  }
+  this->discard_available();
   this->schedule_reboot_();
 }
 

esphome/components/mhz19/mhz19.cpp

@@ -120,9 +120,7 @@ void MHZ19Component::range_set(MHZ19DetectionRange detection_range) {
 }
 
 bool MHZ19Component::mhz19_write_command_(const uint8_t *command, uint8_t *response) {
-  // Empty RX Buffer
-  while (this->available())
-    this->read();
+  this->discard_available();
   this->write_array(command, MHZ19_REQUEST_LENGTH);
   this->write_byte(mhz19_checksum(command));
   this->flush();

esphome/components/pylontech/pylontech.cpp

@@ -99,11 +99,7 @@ void PylontechComponent::dump_config() {
   LOG_UPDATE_INTERVAL(this);
 }
 
-void PylontechComponent::setup() {
-  while (this->available() != 0) {
-    this->read();
-  }
-}
+void PylontechComponent::setup() { this->discard_available(); }
 
 void PylontechComponent::update() {
 #ifdef PYLONTECH_CELL_BATTERY_COUNT

esphome/components/pzem004t/pzem004t.cpp

@@ -9,9 +9,7 @@ namespace esphome::pzem004t {
 ESPHOME_LOG_TAG(TAG, "pzem004t");
 
 void PZEM004T::setup() {
-  // Clear UART buffer
-  while (this->available())
-    this->read();
+  this->discard_available();
   // Set module address
   this->write_state_(SET_ADDRESS);
 }
@@ -19,8 +17,7 @@ void PZEM004T::setup() {
 void PZEM004T::loop() {
   const uint32_t now = App.get_loop_component_start_time();
   if (now - this->last_read_ > 500 && this->available() < 7) {
-    while (this->available())
-      this->read();
+    this->discard_available();
     this->last_read_ = now;
   }
 

esphome/components/shelly_dimmer/shelly_dimmer.cpp

@@ -483,10 +483,7 @@ void ShellyDimmer::reset_(bool boot0) {
   // Wait 50ms for the STM32 to reset.
   delay(50);  // NOLINT
 
-  // Clear receive buffer.
-  while (this->available()) {
-    this->read();
-  }
+  this->discard_available();
 
   this->pin_nrst_->digital_write(true);
   // Wait 50ms for the STM32 to boot.

esphome/components/t6615/t6615.cpp

@@ -32,8 +32,7 @@ void T6615Component::loop() {
   if (this->available() < 5) {
     if (this->command_ == T6615Command::GET_PPM && millis() - this->command_time_ > T6615_TIMEOUT) {
       /* command got eaten, clear the buffer and fire another */
-      while (this->available())
-        this->read();
+      this->discard_available();
       this->send_ppm_command_();
     }
     return;
@@ -48,9 +47,7 @@ void T6615Component::loop() {
   if (response_buffer[0] != T6615_MAGIC || response_buffer[1] != T6615_ADDR_HOST) {
     ESP_LOGW(TAG, "Got bad data from T6615! Magic was %02X and address was %02X", response_buffer[0],
              response_buffer[1]);
-    /* make sure the buffer is empty */
-    while (this->available())
-      this->read();
+    this->discard_available();
     /* try again to read the sensor */
     this->send_ppm_command_();
     this->status_set_warning();

esphome/components/tmc22xx/tmc22xx.cpp

@@ -446,8 +446,7 @@ bool TMC22XXStepper::write_register(uint8_t reg, uint32_t value) {
                                      0};
   datagram[7] = datagram_crc(datagram, 7);
 
-  while (this->available())
-    this->read();
+  this->discard_available();
   this->write_array(datagram, DATAGRAM_SIZE);
   this->flush();
   // On the single wire bus every byte sent is also received, drop that echo
@@ -475,8 +474,7 @@ optional<uint32_t> TMC22XXStepper::read_register(uint8_t reg) {
   uint8_t request[READ_REQUEST_SIZE] = {SYNC_BYTE, this->address_, reg, 0};
   request[3] = datagram_crc(request, 3);
 
-  while (this->available())
-    this->read();
+  this->discard_available();
   this->write_array(request, READ_REQUEST_SIZE);
   this->flush();
   uint8_t reply[DATAGRAM_SIZE];