Re: baudrate detection

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 12/12/2013 07:40 PM, John Whitmore wrote:
> I'm coming from the embedded micro controller end of using CAN and have created
> my own CAN Network nodes. Now I'm working with a MCP2515 connected to the
> Raspberry Pi, so looking at the Linux Kernel.

A SPI based CAN adapter like the mcp2515 are known to have bad
performance, you probably will have better CAN experience with an USB
adapter.

> On my existing nodes the Initialisation of the CAN device the node either knows
> the baudrate to setup or it does not. A node that is a fixed node on the
> network knows the baudrate of the network, although this can be changed on the
> fly. Other devices are not a fixed part of the network and are connected
> dynamically to the network for testing or management purposes. These nodes
> don't know the baudrate of the network so automatically detect it. When they
> detect the baudrate they then connect and inform the higher application code
> that the network is connected, so they can proceed.
> 
> I was thinking of adding this auto baudrate detection functionality to the
> RaspberryPi but being new to Linux development I'm struggling with whether
> this functionality should be in Kernel or User Space. I was initially thinking
> User Space but given that numerous applications can be using the CAN Network
> you really want to centralise this functionality. That possibly means Kernel
> Space?
>
> So before I start to do something I thought I'd ask the experts. Does
> automatic baudrate detection belong in Kernel Space or out in Userland? Maybe
> it's already in the existing Kernel I've just missed it.

I think for prototyping the algorithm you should start in userspace, the
you can present it here and then we can discuss if it's better suited in
a library or in the kernel space.

Marc
-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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