From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752836AbaBMSZp (ORCPT ); Thu, 13 Feb 2014 13:25:45 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:34108 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752239AbaBMSZn (ORCPT ); Thu, 13 Feb 2014 13:25:43 -0500 Date: Thu, 13 Feb 2014 10:27:01 -0800 From: Greg KH To: Russell King - ARM Linux Cc: Tushar Behera , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linux-samsung-soc@vger.kernel.org, jslaby@suse.cz, ben.dooks@codethink.co.uk, broonie@kernel.org Subject: Re: [PATCH 2/2] serial: pl011: Move uart_register_driver call to device probe Message-ID: <20140213182701.GA32578@kroah.com> References: <1390208555-27770-1-git-send-email-tushar.behera@linaro.org> <1390208555-27770-3-git-send-email-tushar.behera@linaro.org> <20140120100415.GX15937@n2100.arm.linux.org.uk> <20140213181216.GB24155@kroah.com> <20140213181559.GB30257@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140213181559.GB30257@n2100.arm.linux.org.uk> User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 13, 2014 at 06:15:59PM +0000, Russell King - ARM Linux wrote: > On Thu, Feb 13, 2014 at 10:12:16AM -0800, Greg KH wrote: > > On Mon, Jan 20, 2014 at 10:04:15AM +0000, Russell King - ARM Linux wrote: > > > On Mon, Jan 20, 2014 at 02:32:35PM +0530, Tushar Behera wrote: > > > > uart_register_driver call binds the driver to a specific device > > > > node through tty_register_driver call. This should typically happen > > > > during device probe call. > > > > > > > > In a multiplatform scenario, it is possible that multiple serial > > > > drivers are part of the kernel. Currently the driver registration fails > > > > if multiple serial drivers with same default major/minor numbers are > > > > included in the kernel. > > > > > > > > A typical case is observed with amba-pl011 and samsung-uart drivers. > > > > > > NAK. There should not be any other driver using amba-pl011's device numbers. > > > > I agree, but there is. And because of that, moving the registration to > > the probe call fixes the issue with building a kernel with all of the > > drivers built into them, so I'm going to take both of these patches, as > > it does solve that problem, while still allowing the device number > > collision to happen. > > So what happens when two _devices_ are probed by this driver at the same > time? The bus that the driver is on will not allow that to happen, I thought we went through this before... And yes, devices on different busses could cause problems, but is that the case here for these devices? At first glance, I don't think that can happen for these drivers. thanks, greg k-h