linux-kernel - Re: [PATCH] allow alternative name for PXA serial console

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Message-ID: <20130312233951.GA32737@kroah.com>
Date:	Tue, 12 Mar 2013 16:39:51 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Сергей Янович <ynvich@...il.com>
Cc:	Jiri Slaby <jslaby@...e.cz>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] allow alternative name for PXA serial console

On Wed, Mar 13, 2013 at 03:34:59AM +0400, Сергей Янович wrote:
> On 13 March 2013 03:10, Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
> > On Wed, Mar 13, 2013 at 03:02:22AM +0400, Sergey Yanovich wrote:
> >> +config SERIAL_PXA_TTYSA_NAME
> >> +     bool "as /dev/ttySA[0-3]"
> >
> > Does that config text really make sense?  What does it look like when
> > you run "make oldconfig"?
> 
> --------------------
> * Non-8250 serial port support
> *
> PXA serial port support (SERIAL_PXA) [Y/n/?] y
>   Console on PXA serial port (SERIAL_PXA_CONSOLE) [Y/n/?] y
>   as /dev/ttySA[0-3] (SERIAL_PXA_TTYSA_NAME) [N/y/?] (NEW)

Please make it sane for the single line it is on.

> So the kernel will have PXA serial port, a console on it, and it will
> have a name (and numbers) /dev/ttySA0 to /dev/ttySA3.
> 
> >> ICP DAS LP-8x4x is an industrial data acquision device. It is based
> >> on PXA270 CPU. The board containsi a lot of (up to 36) standard UARTi
> >> 8250i serial ports. System console on the board is provided with
> >> an on-chip PXA serial port. Both modules use /dev/ttyS0 by default.
> >>
> >> To solve the collision, PXA ports could be configured with different
> >> name and device numbers.
> 
> > Ugh, why does it matter what it is named?
> >
> > Use udev, or a tool like it, to rename serial ports if you really need
> > it, don't do this in the kernel please.
> 
> It doesn't matter what it is named. It matters that both drivers try
> to use the same major device number. I have to change major device
> number for PXA tty, as a result I need a different name in /dev
> 
> Maybe I am missing something obvious, but it seems that such a
> collision is a kernel bug. Someone assumed that PXA cannot have a 8250
> tty device and used 8250's parameters in PXA tty driver.

Yes, someone must have messed up, so care to find the root problem here?

thanks,

greg k-h
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