Esp32-hal-spi.c > polling a bit

Projects Networking, Protocols, and Devices
1

Can someone explain to me why this bit is polled? According to the datasheet it is just a "WT" bit?
I don't understand it

  spi->dev->cmd.update = 1;
  while (spi->dev->cmd.update);

void spiWrite(spi_t *spi, const uint32_t *data, uint8_t len) {
  if (!spi) {
    return;
  }
  int i;
  if (len > 16) {
    len = 16;
  }
  SPI_MUTEX_LOCK();
  spi->dev->mosi_dlen.usr_mosi_dbitlen = (len * 32) - 1;
#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32
  spi->dev->miso_dlen.usr_miso_dbitlen = 0;
#endif
  for (i = 0; i < len; i++) {
#if CONFIG_IDF_TARGET_ESP32C6 || CONFIG_IDF_TARGET_ESP32H2
    spi->dev->data_buf[i].val = data[i];
#else
    spi->dev->data_buf[i] = data[i];
#endif
  }
#if CONFIG_IDF_TARGET_ESP32C2 || CONFIG_IDF_TARGET_ESP32C3 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C6 || CONFIG_IDF_TARGET_ESP32H2
  spi->dev->cmd.update = 1;
  while (spi->dev->cmd.update);
#endif
  spi->dev->cmd.usr = 1;
  while (spi->dev->cmd.usr);
  SPI_MUTEX_UNLOCK();
}
2

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