From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755271AbcEYQGu (ORCPT ); Wed, 25 May 2016 12:06:50 -0400 Received: from foss.arm.com ([217.140.101.70]:35744 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750765AbcEYQGs (ORCPT ); Wed, 25 May 2016 12:06:48 -0400 Date: Wed, 25 May 2016 17:06:33 +0100 From: Mark Rutland To: Frank Rowand Cc: Christer Weinigel , linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org, devicetree@vger.kernel.org, Mark Brown Subject: Re: [PATCH] devicetree - document using aliases to set spi bus number. Message-ID: <20160525160633.GC30956@leverpostej> References: <1464107960-10775-1-git-send-email-christer@weinigel.se> <20160524174140.GE11605@leverpostej> <5745C3F8.4020909@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5745C3F8.4020909@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 25, 2016 at 08:25:44AM -0700, Frank Rowand wrote: > On 5/24/2016 10:41 AM, Mark Rutland wrote: > > On Tue, May 24, 2016 at 06:39:20PM +0200, Christer Weinigel wrote: > >> +Normally SPI buses are assigned dynamic bus numbers starting at 32766 > >> +and counting downwards. It is possible to assign the bus number > >> +statically using devicetee aliases. For example, on the MPC5200 the > >> +"spi@f00" device above is connected to the "soc" bus. To set its > >> +bus_num to 1 add an aliases entry like this: > > > > As Mark Brown pointed out, this is very Linux-specific (at least in the > > wording of the above). > > > > Generally, aliases are there to match _physical_ identifiers (e.g. to > > match physical labels for UART0, UART1, and on). > > Can you point to anything in the specification or any other place that > states that aliases are for matching physical identifiers? > > Can you point to anything in the specification or any other place that > states that aliases are not to be used for anything else? You have me there; I cannot find any wording to that effect, and I am evidently going by my understanding alone. IEEE 1275 simply states that there may be predefined aliases for a machine, or that users can create and use them dynamically. ePAPR (and the devicetree specification) only states that aliases exist, and that a client program might use them (through some means which is never described). Thanks, Mark. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH] devicetree - document using aliases to set spi bus number. Date: Wed, 25 May 2016 17:06:33 +0100 Message-ID: <20160525160633.GC30956@leverpostej> References: <1464107960-10775-1-git-send-email-christer@weinigel.se> <20160524174140.GE11605@leverpostej> <5745C3F8.4020909@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <5745C3F8.4020909-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Frank Rowand Cc: Christer Weinigel , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mark Brown List-Id: devicetree@vger.kernel.org On Wed, May 25, 2016 at 08:25:44AM -0700, Frank Rowand wrote: > On 5/24/2016 10:41 AM, Mark Rutland wrote: > > On Tue, May 24, 2016 at 06:39:20PM +0200, Christer Weinigel wrote: > >> +Normally SPI buses are assigned dynamic bus numbers starting at 32766 > >> +and counting downwards. It is possible to assign the bus number > >> +statically using devicetee aliases. For example, on the MPC5200 the > >> +"spi@f00" device above is connected to the "soc" bus. To set its > >> +bus_num to 1 add an aliases entry like this: > > > > As Mark Brown pointed out, this is very Linux-specific (at least in the > > wording of the above). > > > > Generally, aliases are there to match _physical_ identifiers (e.g. to > > match physical labels for UART0, UART1, and on). > > Can you point to anything in the specification or any other place that > states that aliases are for matching physical identifiers? > > Can you point to anything in the specification or any other place that > states that aliases are not to be used for anything else? You have me there; I cannot find any wording to that effect, and I am evidently going by my understanding alone. IEEE 1275 simply states that there may be predefined aliases for a machine, or that users can create and use them dynamically. ePAPR (and the devicetree specification) only states that aliases exist, and that a client program might use them (through some means which is never described). Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html