Reduce need for UNUSED

Marlin/src/HAL/HAL_AVR/HAL.h

@@ -146,8 +146,7 @@ extern "C" {
 #define DISABLE_TEMPERATURE_INTERRUPT()    CBI(TIMSK0, OCIE0B)
 #define TEMPERATURE_ISR_ENABLED()         TEST(TIMSK0, OCIE0B)
 
-FORCE_INLINE void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency) {
-  UNUSED(frequency);
+FORCE_INLINE void HAL_timer_start(const uint8_t timer_num, const uint32_t) {
   switch (timer_num) {
     case STEP_TIMER_NUM:
       // waveform generation = 0100 = CTC

Marlin/src/HAL/HAL_AVR/HAL_SPI.cpp

@@ -184,15 +184,10 @@ void spiBegin() {
   // nop to tune soft SPI timing
   #define nop asm volatile ("\tnop\n")
 
-  // Set SPI rate
-  void spiInit(uint8_t spiRate) {
-    UNUSED(spiRate);  // nothing to do
-  }
+  void spiInit(uint8_t) { /* do nothing */ }
 
   // Begin SPI transaction, set clock, bit order, data mode
-  void spiBeginTransaction(uint32_t spiClock, uint8_t bitOrder, uint8_t dataMode) {
-    UNUSED(spiBeginTransaction);  // nothing to do
-  }
+  void spiBeginTransaction(uint32_t spiClock, uint8_t bitOrder, uint8_t dataMode) { /* do nothing */ }
 
   // Soft SPI receive byte
   uint8_t spiRec() {

Marlin/src/HAL/HAL_DUE/HAL_SPI.cpp

@@ -151,13 +151,12 @@
     (((uint32_t)(addr) & 0xF0000000) + 0x02000000 + ((uint32_t)(addr)&0xFFFFF)*32 + (bit)*4)
 
   // run at ~8 .. ~10Mhz - Rx version (Tx line not altered)
-  static uint8_t spiTransferRx0(uint8_t bout) { // using Mode 0
+  static uint8_t spiTransferRx0(uint8_t) { // using Mode 0
     uint32_t bin = 0;
     uint32_t work = 0;
     uint32_t BITBAND_MISO_PORT = BITBAND_ADDRESS( ((uint32_t)PORT(MISO_PIN))+0x3C, PIN_SHIFT(MISO_PIN));  /* PDSR of port in bitband area */
     uint32_t SCK_PORT_PLUS30 = ((uint32_t) PORT(SCK_PIN)) + 0x30;    /* SODR of port */
     uint32_t SCK_MASK = PIN_MASK(SCK_PIN);
-    UNUSED(bout);
 
     /* The software SPI routine */
     __asm__ __volatile__(

Marlin/src/HAL/HAL_DUE/MarlinSerialUSB.cpp

@@ -55,12 +55,9 @@ static int pending_char = -1;
 #endif
 
 // Public Methods
-void MarlinSerialUSB::begin(const long baud_setting) {
-  UNUSED(baud_setting);
-}
+void MarlinSerialUSB::begin(const long) {}
 
-void MarlinSerialUSB::end() {
-}
+void MarlinSerialUSB::end() {}
 
 int MarlinSerialUSB::peek() {
   if (pending_char >= 0)

Marlin/src/HAL/HAL_DUE/usb/sd_mmc_spi_mem.cpp

@@ -33,19 +33,12 @@ Ctrl_status sd_mmc_spi_read_capacity(uint32_t *nb_sector) {
   return CTRL_GOOD;
 }
 
-bool sd_mmc_spi_unload(bool unload) {
-  UNUSED(unload);
-  return true;
-}
+bool sd_mmc_spi_unload(bool) { return true; }
 
-bool sd_mmc_spi_wr_protect() {
-  return false;
-}
+bool sd_mmc_spi_wr_protect() { return false; }
 
 bool sd_mmc_spi_removal() {
-  if (!IS_SD_INSERTED() || IS_SD_PRINTING() || IS_SD_FILE_OPEN() || !card.isMounted())
-    return true;
-  return false;
+  return (!IS_SD_INSERTED() || IS_SD_PRINTING() || IS_SD_FILE_OPEN() || !card.isMounted());
 }
 
 #if ACCESS_USB == true

Marlin/src/HAL/HAL_ESP32/watchdog.h

@@ -25,4 +25,4 @@
 void watchdog_init();
 
 // Reset watchdog.
-inline void HAL_watchdog_refresh() { }
+inline void HAL_watchdog_refresh() {}

Marlin/src/HAL/HAL_LINUX/HAL.h

@@ -78,7 +78,7 @@ extern HalSerial usb_serial;
 #define ENABLE_ISRS()
 #define DISABLE_ISRS()
 
-inline void HAL_init() { }
+inline void HAL_init() {}
 
 // Utility functions
 #pragma GCC diagnostic push

Marlin/src/HAL/HAL_LINUX/include/serial.h

@@ -83,9 +83,9 @@ public:
 
   HalSerial() { host_connected = true; }
 
-  void begin(int32_t baud) { }
+  void begin(int32_t) {}
 
-  void end() { }
+  void end() {}
 
   int peek() {
     uint8_t value;

Marlin/src/HAL/HAL_LPC1768/MarlinSerial.h

@@ -49,7 +49,7 @@ public:
     {
     }
 
-  void end() { }
+  void end() {}
 
   #if ENABLED(EMERGENCY_PARSER)
     bool recv_callback(const char c) override {

Marlin/src/HAL/HAL_STM32/HAL.cpp

@@ -104,17 +104,11 @@ extern "C" {
 // ADC
 // ------------------------
 
-void HAL_adc_start_conversion(const uint8_t adc_pin) {
-  HAL_adc_result = analogRead(adc_pin);
-}
+// TODO: Make sure this doesn't cause any delay
+void HAL_adc_start_conversion(const uint8_t adc_pin) { HAL_adc_result = analogRead(adc_pin); }
 
-uint16_t HAL_adc_get_result() {
-  return HAL_adc_result;
-}
+uint16_t HAL_adc_get_result() { return HAL_adc_result; }
 
-void flashFirmware(int16_t value) {
-  UNUSED(value);
-  NVIC_SystemReset();
-}
+void flashFirmware(int16_t) { NVIC_SystemReset(); }
 
 #endif // ARDUINO_ARCH_STM32 && !STM32GENERIC

Marlin/src/HAL/HAL_STM32_F4_F7/HAL.h

@@ -150,7 +150,7 @@ extern uint16_t HAL_adc_result;
 // Memory related
 #define __bss_end __bss_end__
 
-inline void HAL_init() { }
+inline void HAL_init() {}
 
 // Clear reset reason
 void HAL_clear_reset_source();

Marlin/src/HAL/HAL_TEENSY31_32/HAL.h

@@ -87,7 +87,7 @@ typedef int8_t pin_t;
 #undef pgm_read_word
 #define pgm_read_word(addr) (*((uint16_t*)(addr)))
 
-inline void HAL_init() { }
+inline void HAL_init() {}
 
 // Clear the reset reason
 void HAL_clear_reset_source();

Marlin/src/HAL/HAL_TEENSY35_36/HAL.h

@@ -93,7 +93,7 @@ typedef int8_t pin_t;
 #undef pgm_read_word
 #define pgm_read_word(addr) (*((uint16_t*)(addr)))
 
-inline void HAL_init() { }
+inline void HAL_init() {}
 
 // Clear reset reason
 void HAL_clear_reset_source();

Marlin/src/HAL/shared/Delay.h

@@ -53,7 +53,7 @@
 
     FORCE_INLINE static void DELAY_CYCLES(const uint32_t x) {
       const uint32_t endCycles = getCycleCount() + x;
-      while (PENDING(getCycleCount(), endCycles)) { }
+      while (PENDING(getCycleCount(), endCycles)) {}
     }
 
   #else