uart-dma example with changing data length

[usbalbin]

The uart-dma example does not show how to send data with different length using dma.

Is this not supported by this crate or is it even a hardware limitation?

example:

[...]

let data_to_send = [
    &b"Hello"[..], // These are to be sent one at a time to simulate sending messages of different sizes
    &b"I"[..],
    &b"am Bob the Bot"[..],
];


// Setup DMA for USART2 TX with dma channel 1.
let mut transfer =
    streams
        .0
        .into_memory_to_peripheral_transfer(tx.enable_dma(), &mut tx_buffer[..], config);

transfer.start(|_tx| {});
loop {
    while !transfer.get_transfer_complete_flag() {}

    delay_syst.delay(1000.millis());
    led.toggle().unwrap();
    transfer.restart(|_tx| {}); // <---------- Do something here to either change buffer to data_to_send[i],
                                // , or copy to tx_buffer (assuming it is large enough) and tell `transfer` the new data length
}

[usbalbin]

To me I think it would have made more sense if the uart and dma stream were combined into a "uart-with-dma" rather than a "dma-stream-thing that happens to wrap an uart".

So instead of

let mut transfer =
    streams
        .0
        .into_memory_to_peripheral_transfer(tx.enable_dma(), &mut tx_buffer[..], config);

I would want

let mut tx: Tx<UART2, PIN, DMA> = tx.enable_dma(streams.0, &mut tx_buffer[..]);

since Tx<UART2, PIN, DMA> can then impl core::fmt::Write(or some more appropriate alternative), set senseful dma configs automatically etc since it has more knowledge of how the dma channel will be used.

Any thoughts? :)