Subject: Re: lanana: Add major/minor entries for PPC QE UART devices

From: Timur Tabi <[email-masked]>
Date: Wed, 28 Feb 2007 11:04:04 -0600

Dan Malek wrote:

> I don't know the origin of this thread, but none of
> that looks correct.  Today, there can be up to 8
> CPM UART devices, 6 on CPM/CPM2 and 8
> on the QE.  If ttyCPM0 starts at minor 46, they
> should be at least monotonically incrementing
> up to ttyCPM7 with minor 53.

Minor nit: On the QE, they'll be called ttyQE0 through ttyQE7.

I agree that the CPM and the QE should share the same starting minor number, so that 
ttyCPM0 has the same major/minor number as ttyQE0, since it's not possible to have a CPM 
and a QE on the same device.  However, ttyCPM0 is currently assigned to 46, and device 50 
is an Altix serial card.  The only way to give the CPM 6 or 8 slots without moving it is 
to overlap the Altix card.

Now I don't know anything about the Altix card, so I don't know if it's possible to use 
that card on a system with a CPM or a QE.  If it isn't, then I don't know if overlapping 
minor numbers is still a problem.

(Note that the Altix card has a range of 50-81, which is pretty big.)

If we move CPM/QE to 192, then I can change the CPM device driver to reflect that, but I 
don't know what that means for older kernels.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale