Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933332AbdCaN2C (ORCPT ); Fri, 31 Mar 2017 09:28:02 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:43808 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932927AbdCaN17 (ORCPT ); Fri, 31 Mar 2017 09:27:59 -0400 Date: Fri, 31 Mar 2017 15:27:42 +0200 From: Greg Kroah-Hartman To: Geert Uytterhoeven Cc: Russell King - ARM Linux , Sjoerd Simons , "linux-serial@vger.kernel.org" , Linux-Renesas , "linux-kernel@vger.kernel.org" , Jiri Slaby Subject: Re: [PATCH 0/2] Move uart_register_driver call to device probe for pl010 and sh-sci Message-ID: <20170331132742.GA23739@kroah.com> References: <20170324162634.8880-1-sjoerd.simons@collabora.co.uk> <20170324164202.GI7909@n2100.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1794 Lines: 47 On Sun, Mar 26, 2017 at 11:22:57AM +0200, Geert Uytterhoeven wrote: > Hi Russell, Sjoerd, > > On Fri, Mar 24, 2017 at 5:42 PM, Russell King - ARM Linux > wrote: > > On Fri, Mar 24, 2017 at 05:26:32PM +0100, Sjoerd Simons wrote: > >> When testing on a Renesas board with the PL010 serial driver enabled > >> serial output broke. Turns out the minor device numbers for both > >> drivers happen to overlap, causing whichever driver happened to be the > >> second one to register to fail. > > > > How the **** has the SH serial driver ended up with overlapping device > > numbers? > > Interesting... > > > What happened to our maintained list of allocated major/minor device > > numbers, which is supposed to stop crap like this happening? > > AMBA PL010 has been assigned major 204, minors 16..31, > SCI has been assigned major 204, minors 8..11. > > Over the years, Renesas SoCs have been gaining more and more serial > ports, leading to > > #define SCI_NPORTS CONFIG_SERIAL_SH_SCI_NR_UARTS > > with CONFIG_SERIAL_SH_SCI_NR_UARTS=20 in shmobile_defconfig and > multi_v7_defconfig (although the maximum value on any supported SoC is 18). > > But once the value becomes 5 or more, it starts overflowing into the ttyFWx > and ttyAMx space. > > How to solve this? > Time for the serial subsystem to switch to dynamic minors, and get rid of the > what-is-your-serial-port-called-again-on-this-platform > multi-million-euro question? Yes, please, we need to do that. Let's provide a build option for it, like USB has had for over a decade. If it's enabled, it's all dynamic, if not, the "old style" ones are used. Then we don't accept any new reservations, making new drivers use the dynamic number, and over a long time, all should be good. thanks, greg k-h