Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751834Ab3HTPfH (ORCPT ); Tue, 20 Aug 2013 11:35:07 -0400 Received: from mail-pb0-f49.google.com ([209.85.160.49]:41733 "EHLO mail-pb0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751810Ab3HTPfC (ORCPT ); Tue, 20 Aug 2013 11:35:02 -0400 Date: Tue, 20 Aug 2013 08:34:56 -0700 From: Guenter Roeck To: Mark Rutland Cc: Oleksandr Kozaruk , "grant.likely@linaro.org" , "rob.herring@calxeda.com" , "rob@landley.net" , "linux-doc@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jonathan Cameron Subject: Re: [PATCH] iio: adc: Add bindigs documentation for twl6030 GPADC Message-ID: <20130820153456.GA12618@roeck-us.net> References: <1376911765-7821-1-git-send-email-oleksandr.kozaruk@ti.com> <20130820091228.GW3719@e106331-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130820091228.GW3719@e106331-lin.cambridge.arm.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 Content-Length: 2741 Lines: 59 On Tue, Aug 20, 2013 at 10:12:28AM +0100, Mark Rutland wrote: > Hi Oleksandr, > > [Adding Jonathan Cameron and Guenter Roeck to Cc] > > Apologies for the delay replying to this. In attempting to verify this > made sense I went and read the IIO bindings documentation, and I'm > somewhat confused by the model. > > As far as I can see, the only consumer of IIO channels is the > "iio-hwmon" binding, which seems to be a binding for Linux-specific > infrastructure rather than any actual device. This runs counter to the In respect to "iio-hwmon", I think you may actually be correct; we should have found a better means to describe the system. The intend was to describe that a set of adc inputs is connected to a set of voltages or temperature sensors. Is there a better way ? I am sure there is, but I have no idea what it might be, nor do I have the time to find out. However, I think that the "io-channels" property is well defined. "gpios" describes a group of gpio pins which have a common purpose. "io-channels" describes a group of io channels (or, ultimately, pins) which have a common purpose. So this is not really linux specific, unless other operating systems don't see the need of describing a group of io channels as single entity. But then the same could be claimed about groups of gpio pins. > way DT is supposed to function (describing the hardware rather than how > it's used). As far as I can see, this linkage is described because only > a subset of the ADCs on the device are actually wired to something? > Is that a problem ? I would think that the same is true for many chips with multiple inputs and/or outputs. > I also see a couple of IIO bindings ("adi,adf435x*, and "adi,ad7303") > which don't describe any iio channel cells at all, so I'm somewhat > confused by what the IIO channels actually represent, and why they must > be consumed elsewhere. As far as I can see, an IIO channel represents a > single ADC's registers in an IIO device, so I'm not sure why this must > be exported via the channel concept -- it's not physically wired. > I am sure there would be some other means to describe the same, so I would agree that it does not _have_ to be the way it is. Question is if there is a better way. Again, "io-channels" describes a group of io channels with a common purpose. Sure, that does not _have_ to be described as a single property, but then I could argue that the same is true for "gpios" and probably many other properties. Thanks, Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/