Resetting CNDTR for UART DMA method

That was the answer that was doing exactly what I was searching for. Another way to write it using HAL :

/*
* Reset your SPI RX DMA Buffer
*/
void reset_spi_dma_rx_buffer(SPI_HandleTypeDef hspi, int rx_buffer_size) {
 __HAL_DMA_DISABLE(hspi.hdmarx);
 hspi.hdmarx->Instance->CNDTR = rx_buffer_size; // reset counter
 __HAL_DMA_ENABLE(hspi.hdmarx);
}

I attach this function to SPI CS(aka SS) on interrupt of rising edge (end of SPI transaction):

void HAL_GPIO_EXTI_Rising_Callback(uint16_t GPIO_Pin) {
 if (GPIO_Pin == GPIO_PIN_5) {
 reset_spi_dma_rx_buffer(hspi2, sizeof(buffer_rx_spi2));
 }
}

This way, if the count data buffer is too small (or bigger), the buffer is init and ready for a new Message. I use DMA circular.