From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757474Ab3AYQOM (ORCPT ); Fri, 25 Jan 2013 11:14:12 -0500 Received: from service87.mimecast.com ([91.220.42.44]:54682 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757174Ab3AYQOJ convert rfc822-to-8bit (ORCPT ); Fri, 25 Jan 2013 11:14:09 -0500 Date: Fri, 25 Jan 2013 16:14:02 +0000 From: Mark Rutland To: Felipe Balbi Cc: Kishon Vijay Abraham I , "rob.herring@calxeda.com" , "rob@landley.net" , "tony@atomide.com" , "b-cousson@ti.com" , "linux-usb@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-omap@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , "gregkh@linuxfoundation.org" , "linux@arm.linux.org.uk" Subject: Re: [PATCH v4 1/4] drivers: usb: phy: add a new driver for usb part of control module Message-ID: <20130125161401.GD16795@e106331-lin.cambridge.arm.com> References: <1359109440-2195-1-git-send-email-kishon@ti.com> <1359109440-2195-2-git-send-email-kishon@ti.com> <20130125110141.GK3075@e106331-lin.cambridge.arm.com> <20130125111120.GP15886@arwen.pp.htv.fi> <20130125122943.GB16795@e106331-lin.cambridge.arm.com> <20130125145928.GC28379@arwen.pp.htv.fi> MIME-Version: 1.0 In-Reply-To: <20130125145928.GC28379@arwen.pp.htv.fi> User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginalArrivalTime: 25 Jan 2013 16:14:02.0927 (UTC) FILETIME=[FDC8F3F0:01CDFB16] X-MC-Unique: 113012516140700801 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 25, 2013 at 02:59:28PM +0000, Felipe Balbi wrote: > Hi, > > On Fri, Jan 25, 2013 at 12:29:43PM +0000, Mark Rutland wrote: > > > > > + depending upon omap4 or omap5. > > > > > + - reg-names: The names of the register addresses corresponding to the registers > > > > > + filled in "reg". > > > > > + - ti,type: This is used to differentiate whether the control module has > > > > > + usb mailbox or usb3 phy power. omap4 has usb mailbox in control module to > > > > > + notify events to the musb core and omap5 has usb3 phy power register to > > > > > + power on usb3 phy. Should be "1" if it has mailbox and "2" if it has usb3 > > > > > + phy power. > > > > > > > > Why not make this a string property, perhaps values "mailbox" or "register"? > > > > > > NAK. > > > > Can I ask what your objection to using a string property is? > > > > As far as I can see, "ti,type" is only used by this driver, so there's no > > common convention to stick to. Using a string makes the binding easier for > > humans to read, and thus harder to mess up in a dts, and it decouples the > > binding from kernel-side constants. > > IIRC there is some work going on to add #define-like support for DT, > which would allow us to match against integers while still having > meaningful symbolic representations. I was under the impression that the motivation for using the preprocessor on the DT was to allow symbolic names for device/soc-specific values like addresses, rather than what amounts to ABI values for the binding. I don't see the point in building a binding that depends on future functionality to be legible, especially as we can make it more readable, robust, and just as extensible today, with a simple change to the proposed binding. Even ignoring the above, the driver isn't doing appropriate sanity checking. If you use a string property, this sanity check is implicit in the parsing -- you've either matched a value you can handle or you haven't. Thanks, Mark.