[PATCH 05/15] tty: serial: Add 8250-core based omap driver

On 08/15/2014 09:33 PM, Lennart Sorensen wrote:

quoted

On the other hand if you use DMA then it can handle transfers > 64bytes
in one go and you can start transfers while the FIFO is not completely
empty.

You can dma more than the fifo size?

Yes. The UART asserts the DMA line as long as there is room for
$TRESHOLD number of bytes. So we never overflow the FIFO. That is why we
can't take any DMA channel but only *the* one.

quoted

There is patch in Greg's tty tree already where you are able to
configure the RX trigger level. We could wire this up once we agree
which levels we want support. The OMAP supports all levels from 1?63.

All? or just every 4 (that's what I just read in the DRA7xx docs).

All. Take a look at the RX_TRIGGER constant while comparing source vs
manual :)

Sebastian