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Message-ID: <alpine.LFD.2.03.1305081239260.13109@syhkavp.arg>
Date: Wed, 8 May 2013 12:45:12 -0400 (EDT)
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: Arnd Bergmann <arnd@...db.de>
cc: Greg KH <gregkh@...uxfoundation.org>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
Srinivas KANDAGATLA <srinivas.kandagatla@...com>,
Viresh Kumar <viresh.kumar@...aro.org>,
Will Deacon <will.deacon@....com>, jslaby@...e.cz,
Russell King <linux@....linux.org.uk>,
Samuel Ortiz <sameo@...ux.intel.com>,
linux-doc@...r.kernel.org,
Stephen Gallimore <stephen.gallimore@...com>,
linux-serial@...r.kernel.org, Jason Cooper <jason@...edaemon.net>,
devicetree-discuss@...ts.ozlabs.org,
Rob Herring <rob.herring@...xeda.com>,
Stuart Menefy <stuart.menefy@...com>,
Stephen Warren <swarren@...dia.com>,
Dong Aisheng <dong.aisheng@...aro.org>,
linux-arm-kernel@...ts.infradead.org,
Mark Brown <broonie@...nsource.wolfsonmicro.com>,
linux-kernel@...r.kernel.org
Subject: Re: [RFC 1/8] serial:st-asc: Add ST ASC driver.
On Wed, 8 May 2013, Arnd Bergmann wrote:
> On Wednesday 08 May 2013, Greg KH wrote:
> > > just mention there is not hardware reason to not use the generic ttySx
> > > in place of ttyAS as we have only one IP that handle serial on this
> > > family of SoC
> > >
> > > personally I'll switch to ttySx
> >
> > Great, then you can use the same major/minor range as well, so there's
> > no more objection from me about this :)
>
> Does that work these days when you have kernel with multiple built-in
> uart drivers?
>
> I think it would be good if all uarts were using the same name space
> and major/minor numbers, but I think the mess we currently have is
> the result of the tty_register_driver() interface reserving the
> device number range at driver load time, independent of the presence
> of devices. I would assume that normal distro kernels always ship
> with an 8250 driver built-in to allow using that as the console,
> and if I read the code correctly, that currently prevents another
> uart driver from registering the same major/minor numbers.
I tried to fix this up over 10 years ago. RMK tried as well. This
failed because X86 people insisted on always having COM1 as /dev/ttyS0,
COM3 as /dev/ttyS2 and so on, even when some of them weren't present.
A common and dynamic namespace eventually succeeded for hard disks.
Maybe people are ready to accept it for serial ports as well now?
Nicolas
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