Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751936Ab1BZPWs (ORCPT ); Sat, 26 Feb 2011 10:22:48 -0500 Received: from imr4.ericy.com ([198.24.6.8]:51623 "EHLO imr4.ericy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751561Ab1BZPWr (ORCPT ); Sat, 26 Feb 2011 10:22:47 -0500 Date: Sat, 26 Feb 2011 07:21:46 -0800 From: Guenter Roeck To: Jonathan Cameron CC: Jean Delvare , Jonathan Cameron , Randy Dunlap , Greg Schnorr , "lm-sensors@lm-sensors.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v4 4/5] hwmon: (pmbus) Add support for Maxim MAX34440/MAX34441 Message-ID: <20110226152146.GB16108@ericsson.com> References: <1297969217-9564-1-git-send-email-guenter.roeck@ericsson.com> <1297969217-9564-5-git-send-email-guenter.roeck@ericsson.com> <4D681425.3010503@cam.ac.uk> <1298669577.1735.99.camel@groeck-laptop> <4D68D965.7040307@cam.ac.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <4D68D965.7040307@cam.ac.uk> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2720 Lines: 64 On Sat, Feb 26, 2011 at 05:43:49AM -0500, Jonathan Cameron wrote: > On 02/25/11 21:32, Guenter Roeck wrote: > > Hi Jonathan, > > > > On Fri, 2011-02-25 at 15:42 -0500, Jonathan Cameron wrote: > >> One trivial formatting nitpick. > >> Dug out datasheet for this one.. > >> I'm a little unclear how value from there map to those stored in here... > > [ ... ] > > > >>> +static struct pmbus_driver_info max34440_info[] = { > >>> + [max34440] = { > >>> + .pages = 14, > >>> + .direct[PSC_VOLTAGE_IN] = true, > >>> + .direct[PSC_VOLTAGE_OUT] = true, > >>> + .direct[PSC_TEMPERATURE] = true, > >>> + .direct[PSC_CURRENT_OUT] = true, > >>> + .m[PSC_VOLTAGE_IN] = 1, > >>> + .b[PSC_VOLTAGE_IN] = 0, > >>> + .R[PSC_VOLTAGE_IN] = 3, > >>> + .m[PSC_VOLTAGE_OUT] = 1, > >>> + .b[PSC_VOLTAGE_OUT] = 0, > >>> + .R[PSC_VOLTAGE_OUT] = 3, > >>> + .m[PSC_CURRENT_OUT] = 1, > >>> + .b[PSC_CURRENT_OUT] = 0, > >>> + .R[PSC_CURRENT_OUT] = 3, > >> Table 3 of datasheet says R for current is 0... I may be missing > >> something though! > > > > At least this one has a relatively simple reason ;). > > > > The base unit (to which R is applied to) in the datasheet is mV and mA. > > The base unit used by max8688 and max16064 is V and A. Chips in linear > > mode also use V and A. I had the choice of either adjusting the code to > > expect mV and mA for all chips, or to expect V and A for all chips. I > > decided to use the latter for consistency, and to adjust R in the core > > driver to the units expected to be reported in the sysfs attributes. For > > max34440/max34441, the adjustment ends up being 0 either way (3 + (-3) > > in one direction and (-3) + 3 in the other). > This reason actually occurred to me whilst cycling home but thanks for > clarifying this. > > > > Another option would be to not do any sysfs related adjustments in the > > core driver, but to do all adjustments via platform data instead. I > > decided against that because the code to handle linear mode (which > > expects V and A) would no longer match the code to handle direct mode, > > which might cause even more confusion. > What you have works fine for me though you'll have to keep a close eye > on any drivers submitted by others as this will be easy to get wrong > as people will blindly fill tables in from datasheets. > ... though they should really test the code before submitting it. But you are definitely right. > Acked-by: Jonathan Cameron 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/