RFC: delete UART current-speed from 4xx DTS?

[Josh Boyer]

On Thu, Sep 17, 2009 at 07:31:06AM +1000, Benjamin Herrenschmidt wrote:
>
>> Ok, so I think that is related to what I originally hit.
>> 
>> I played around with removing the current-speed property on canyonlands today,
>> and noticed that I would get no console output at all unless I specified a
>> baudrate with console=ttyS0,115200.  That was sort of contrary to what I found
>> with bamboo, so I diffed the configs to see why.  Bamboo has udbg enabled and
>> hence has legacy_serial builtin, whereas canyonlands just has of_serial.
>> 
>> So on boards where of_serial is the only serial driver, we need either an
>> accurate current-speed property, or a specific baudrate on the command line.
>> That makes a bit more tenuous to remove the properties entirely, because if
>> people disable udbg and are relying on that behavior they get no more console
>> output.  Need to think on that a bit I guess.
>> 
>> Alternatively, we could try patching of_serial.c to do the baudrate probe
>> as well.
>
>Well, I've always wondered why we just don't put the probe in the 8250
>driver... I proposed it on the list a while back and there was no

Probably because anything to do with the serial drivers or tty layer scares
the living hell out of people other than Alan and Andrew.  And I sometimes
think even Andrew is faking...

;)

>serious objection, but then forgot about it :-)
>
>We should do it, and check if the result is sane (looks like a standard
>speed). If it is, we should then just used it.

Sounds sane enough.  I'm hoping to get some time in the next few days to
poke at this.

josh