Hi,

On Sun, Aug 21, 2016 at 09:50:57AM +0200, H. Nikolaus Schaller wrote:

quoted

Am 20.08.2016 um 15:34 schrieb One Thousand Gnomes [off-list ref]:

quoted

What it is not about are UART/RS232 converters connected through USB or virtual
serial ports created for WWAN modems (e.g. /dev/ttyACM, /dev/ttyHSO). Or BT devices
connected through USB (even if they also run HCI protocol).

It actually has to be about both because you will find the exact same
device wired via USB SSIC/HSIC to a USB UART or via a classic UART. Not is
it just about embedded boards. 

Not necessarily.

We often have two interface options for exactly the sam sensor chips. They can be connected
either through SPI or I2C. Which means that there is a core driver for the chip and two different
transport glue components (see e.g. iio/accel/bmc150).

This does not require I2C to be able to handle SPI or vice versa or provide a common API.

I don't understand this comparison. I2C and SPI are different
protocols, while native UART and USB-connected UART are both UART.

And most Bluetooth devices I know have either UART or a direct
USB interface. So in the USB case there is no need to connect
it through some USB-UART bridge and treat it as an UART at all.

I think having support for USB-UART dongles is useful for
driver development and testing on non-embedded HW.

-- Sebastian