Serial: sc26xx device name

Serial: sc26xx device name

[Martin Fuzzey]

Hi all,
I noticed the sc26xx driver uses ttySC205 / ttySC206 for device name.

grep ttySC Documentation/devices.txt gives
          8 = /dev/ttySC0        SCI serial port (SuperH) - port 0
          9 = /dev/ttySC1        SCI serial port (SuperH) - port 1
         10 = /dev/ttySC2        SCI serial port (SuperH) - port 2
         11 = /dev/ttySC3        SCI serial port (SuperH) - port 3
         205 = /dev/ttySC0        SC26xx serial port 0
         206 = /dev/ttySC1        SC26xx serial port 1
         207 = /dev/ttySC2        SC26xx serial port 2
         208 = /dev/ttySC3        SC26xx serial port 3
          8 = /dev/cusc0        Callout device for ttySC0
          9 = /dev/cusc1        Callout device for ttySC1
         10 = /dev/cusc2        Callout device for ttySC2
         11 = /dev/cusc3        Callout device for ttySC3

Removing the line:
    sc26xx_reg.tty_driver->name_base = sc26xx_reg.minor;
makes it revert to ttySC0

So two questions:
1) Who is right (the driver or devices.txt)?
2) How are device name conflicts handled?

Cheers,

Martin

Re: Serial: sc26xx device name

[Alan Cox]

> So two questions:
> 1) Who is right (the driver or devices.txt)?

devices.txt has all the officially properly registered values

> 2) How are device name conflicts handled?

Badly - they should never occur but if someone didn't properly reserve
the namespace they can and then whoever forgot to reserve the namespace
loses.

Re: Serial: sc26xx device name

[Martin Fuzzey]

Alan Cox wrote:
>> 2) How are device name conflicts handled?
>>     
>
> Badly - they should never occur but if someone didn't properly reserve
> the namespace they can and then whoever forgot to reserve the namespace
> loses.
>   
Currently this can't happen because the sc26xx driver uses ttySC205
in contradiction to ttySC0 shown in devices.txt

However if the driver were to be  "fixed" to use the name registered
in devices.txt a conflict could occur if a sc26xx chip were used on
a superH system.

The problem seems to be that while the major/minor numbers in devices.txt
are unique (and the drivers are correctly using their registered numbers),
the _names_ are not unique (at least in this case - I haven't checked for
others).

Re: Serial: sc26xx device name

[Alan Cox]

On Sat, 21 Nov 2009 15:23:32 +0100
Martin Fuzzey <mfuzzey@gmail.com> wrote:

> Alan Cox wrote:
> >> 2) How are device name conflicts handled?
> >>     
> >
> > Badly - they should never occur but if someone didn't properly reserve
> > the namespace they can and then whoever forgot to reserve the namespace
> > loses.
> >   
> Currently this can't happen because the sc26xx driver uses ttySC205
> in contradiction to ttySC0 shown in devices.txt

I'd suggest that someone fixes it when it happens in that case. I doubt
it ever will.