Re: [RFC PATCH 0/3] UART slave device bus

Sebastian Reichel
2016-08-22T20:40:06Z

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Hi,

On Sun, Aug 21, 2016 at 09:50:57AM +0200, H. Nikolaus Schaller wrote:
> > Am 20.08.2016 um 15:34 schrieb One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>:
> >> 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

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