Re: [PATCH] serial: DCC(JTAG) serial and console emulation support

Daniel Walker
2010-10-07T20:36:35Z

On Thu, 2010-10-07 at 21:50 +0100, Alan Cox wrote:
> > + Say Y here if you want to install DCC driver as a normal serial port
> > + /dev/ttyS0 (major 4, minor 64). Otherwise, it appears as /dev/ttyJ0
> > + (major 4, minor 128) and can co-exist with other UARTs, such as
> > + 8250/16C550 compatibles.
> > +
>
> NAK to both

Both what?

> ttyJ0 is 204,186 for "JTAG1 DCC protocol based serial"
>
> so there is an existing name and minor allocation, which as you won't be
> using two of them should be quite usable.
>
> If you want to be able to switch at runtime to pretend it is ttyS0 please
> deal with that in your user space. The same rules apply to you as have
> been applied to everyone else who has tried to implement this same crap
> in their uart driver too (we'd have it in about 30 by now otherwise)

I would agree if this wasn't strictly for debugging embedded devices in
difficult situations.. After talking to Mike, it's seems like it would
be useful to have this as a ttyS* specifically because embedded devices
won't always create a ttyJ* for you and ttyS* will likely already exist.

Daniel

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