From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH 2/2] tty: serial: bcm63xx: Allow device nodes to be renamed to /dev/ttyBCM* Date: Tue, 11 Nov 2014 03:30:56 +0900 Message-ID: <20141110183056.GA14178@kroah.com> References: <1415523348-4631-1-git-send-email-cernekee@gmail.com> <1415523348-4631-2-git-send-email-cernekee@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: stable-owner@vger.kernel.org To: Kevin Cernekee Cc: Rob Herring , Jiri Slaby , Grant Likely , Florian Fainelli , Maxime Bizon , Jonas Gorski , Linux-MIPS , "linux-serial@vger.kernel.org" , "devicetree@vger.kernel.org" , stable@vger.kernel.org List-Id: devicetree@vger.kernel.org On Mon, Nov 10, 2014 at 07:05:14AM -0800, Kevin Cernekee wrote: > On Mon, Nov 10, 2014 at 6:25 AM, Rob Herring wrote: > > On Sun, Nov 9, 2014 at 2:55 AM, Kevin Cernekee wrote: > >> By default, bcm63xx_uart.c uses the standard 8250 device naming and > >> major/minor numbers. There are at least two situations where this could > >> be a problem: > >> > >> 1) Multiplatform kernels that need to support some chips that have 8250 > >> UARTs and other chips that have bcm63xx UARTs. > >> > >> 2) Some older chips like BCM7125 have a mix of both UART types. > >> > >> Add a new Kconfig option to tell the driver whether to register itself > >> as ttyS or ttyBCM. By default it will retain the existing "ttyS" > >> behavior to avoid surprises. > > > > While I understand the desire to have stable names, this is the > > opposite direction we want to go. Per platform tty names complicates > > having a generic userspace. It is not so bad since most ARM platforms > > use ttyS or ttyAMA, but just think what the kernel and userspace side > > would look like if every single platform did this. We can't change > > everything to ttyS because the other names are already an ABI. > > > > This can be solved with a udev rule to create sym links. > > Is it safe to register two console drivers named "ttyS" with the same > major/minor numbers? Not at all, think about what you are asking for here. Is the kernel allowed to register two block devices with the same major/minor numbers? greg k-h