linux-kernel - Re: 8250.nr_uarts broken in 3.7

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Date:	Fri, 8 Mar 2013 09:39:23 +0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Josh Boyer <jwboyer@...hat.com>
Cc:	Jiri Slaby <jslaby@...e.cz>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: 8250.nr_uarts broken in 3.7

On Thu, Mar 07, 2013 at 08:01:40PM -0500, Josh Boyer wrote:
> On Fri, Mar 08, 2013 at 07:12:42AM +0800, Greg Kroah-Hartman wrote:
> > On Thu, Mar 07, 2013 at 04:14:27PM -0500, Josh Boyer wrote:
> > > On Thu, Mar 07, 2013 at 02:10:05PM -0500, Josh Boyer wrote:
> > > > On Thu, Mar 07, 2013 at 08:07:23PM +0100, Jiri Slaby wrote:
> > > > > On 03/07/2013 07:56 PM, Josh Boyer wrote:
> > > > > > commit 835d844d1a28efba81d5aca7385e24c29d3a6db2
> > > > > > Author: Sean Young <sean@...s.org>
> > > > > > Date:   Fri Sep 7 19:06:23 2012 +0100
> > > > > > 
> > > > > >     8250_pnp: do pnp probe before legacy probe
> > > > > > 
> > > > > > but that is simply moving code around.
> > > > > 
> > > > > Hi, not quite. Does it still happen when you revert that one on the top
> > > > > of 3.[789]*?
> > > > 
> > > > That was going to be my first attempt.  I'll let you know how it goes.
> > > 
> > > Yes, reverting just 835d844d1 on top of 3.7.0 fixes it.  I also see why
> > > now.  That commit changed the module name from 8250 to 8250_core in the
> > > makefile, so clearly 8250.nr_uarts = 16 isn't going to get parsed.
> > > Adding 8250_core.nr_uarts = 16 seems to work fine.  This wasn't
> > > immediately obvious because the whole thing is built-in and not a
> > > module.  Thankfully, looking in /sys/modules/ still works and that
> > > showed up pretty clearly.
> > > 
> > > So I guess this isn't really a break in functionality as much as it's a
> > > driver rename.  Not sure if it's worth fixing in some form or not.
> > 
> > Yes it needs to be fixed, we shouldn't break userspace stuff like that.
> > Patches gladly accepted.
> 
> OK... well I don't think renaming it back to 8250 is going to actually
> work.  It's already been renamed for 2 releases now, and a renaming
> isn't appropriate for 3.8.y.
> 
> I don't remember exactly, but I don't think simply adding a modalias to
> 8250 will work either.
> 
> So basically, the only way to fix this that I can see is to create a
> new, additional module parameter or something similar that parses
> "8250.nr_uarts".  Is that what you had in mind?

I think that's the only way we can properly solve this, so yes, that
would be good.

thanks,

greg k-h
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