From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760145Ab2DKMzc (ORCPT ); Wed, 11 Apr 2012 08:55:32 -0400 Received: from ppsw-51.csi.cam.ac.uk ([131.111.8.151]:58503 "EHLO ppsw-51.csi.cam.ac.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752785Ab2DKMzb (ORCPT ); Wed, 11 Apr 2012 08:55:31 -0400 X-Cam-AntiVirus: no malware found X-Cam-SpamDetails: not scanned X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Message-ID: <4F857F3F.5080701@cam.ac.uk> Date: Wed, 11 Apr 2012 13:55:27 +0100 From: Jonathan Cameron User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:11.0) Gecko/20120327 Thunderbird/11.0.1 MIME-Version: 1.0 To: Alan Cox CC: Mark Brown , mingo@elte.hu, linux-kernel@vger.kernel.org, Jonathan Cameron , Greg Kroah-Hartman Subject: Re: [PATCH RESEND] x86, intel_mid: ADC management References: <20120410131206.GB31551@sirena.org.uk> <20120410142501.6045c6c0@pyramind.ukuu.org.uk> <20120410133339.GK7499@opensource.wolfsonmicro.com> <20120410144235.1e05efd4@pyramind.ukuu.org.uk> <20120410140749.GL7499@opensource.wolfsonmicro.com> <20120410151529.5bcc5ce6@pyramind.ukuu.org.uk> <20120410151943.GM7499@opensource.wolfsonmicro.com> <20120410175632.5c11c36e@pyramind.ukuu.org.uk> <20120410175846.GQ7499@opensource.wolfsonmicro.com> <20120411112411.11825eec@pyramind.ukuu.org.uk> <20120411103827.GH3163@opensource.wolfsonmicro.com> <4F856173.8000901@cam.ac.uk> <20120411121309.4b8f8e40@pyramind.ukuu.org.uk> <4F8568A8.5060206@cam.ac.uk> <20120411133035.25fa00b0@pyramind.ukuu.org.uk> In-Reply-To: <20120411133035.25fa00b0@pyramind.ukuu.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/11/2012 1:30 PM, Alan Cox wrote: >> needs to be abstracted as well. Consumers might not care that the gain >> just doubled because someone else requested it, but I suspect many of them will. > At the bottom layer I'd expect a second consumer of the same data to get > -EBUSY, but you are then going to tell me there are ADCs with one gain > control for several channels no doubt 8) yup. If you can think of it, someone hardware guy will have implemented it! In this case often comes down to the fact that most adcs are actually a mux on the front of a single channel and the pga may be before the mux or after it (or for a laugh, sometimes both). A real 'fun' one is devices that do scan reads. That is you can only read certain combinations of channels at a time and sometimes those combinations are far from obvious... > > >> end up with most of IIO. That's effectively what we did... It's big >> because there are >> actually not that many 'simple' adc's out there. > Fair enough - you would be the expert there. I just wish they were all simple!