From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752277AbdLKITK (ORCPT ); Mon, 11 Dec 2017 03:19:10 -0500 Received: from mail.free-electrons.com ([62.4.15.54]:53175 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750759AbdLKITI (ORCPT ); Mon, 11 Dec 2017 03:19:08 -0500 Subject: Re: [PATCH 2/8] iio: adc: axp20x_adc: add support for AXP813 ADC To: Jonathan Cameron Cc: sre@kernel.org, robh+dt@kernel.org, mark.rutland@arm.com, wens@csie.org, linux@armlinux.org.uk, maxime.ripard@free-electrons.com, lee.jones@linaro.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-iio@vger.kernel.org, icenowy@aosc.io, linux-sunxi@googlegroups.com, thomas.petazzoni@free-electrons.com References: <20171210163655.43fbd3c0@archlinux> From: Quentin Schulz Message-ID: Date: Mon, 11 Dec 2017 09:18:55 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20171210163655.43fbd3c0@archlinux> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jonathan, On 10/12/2017 17:36, Jonathan Cameron wrote: > On Mon, 4 Dec 2017 15:12:48 +0100 > Quentin Schulz wrote: > >> The X-Powers AXP813 PMIC is really close to what is already done for >> AXP20X/AXP22X. >> >> There are two pairs of bits to set the rate (one for Voltage and Current >> measurements and one for TS/GPIO0 voltage measurements) instead of one. > > This would normally imply we need to split the device into two logical > IIO devices. However, that only becomes relevant if we are using > buffered output which this driver doesn't support. > > It'll be nasty to deal with this if we add that support down the line > though. Up to you though as it's more likely to be your problem than > anyone else's :) > I have no plans for supporting buffered output for the AXPs at the moment. But that's an interesting (and important) limitation to raise. Wouldn't be more of a hack to have two IIO devices representing the actual same IP? > For now you could elect to support the different sampling frequencies > if you wanted to but just providing controls for each channel. > I guess that you're offering to use IIO_CHAN_INFO_SAMP_FREQ in info_mask_separate for each channel? > Given the driver doesn't currently expose these at all (I think) > this is all rather immaterial ;) I'm not giving the user the option to chose the sampling frequency for now. I have no plans to do it either, but I think it would be rather simple to later add support for setting frequency sampling since we only need to add a sysfs entry (with IIO_CHAN_INFO_SAMP_FREQ) that does not exist yet. Don't you think? Am I missing something? Thanks, Quentin -- Quentin Schulz, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com