From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751544AbcGWK4G (ORCPT ); Sat, 23 Jul 2016 06:56:06 -0400 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:53956 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751294AbcGWKzy (ORCPT ); Sat, 23 Jul 2016 06:55:54 -0400 Subject: Re: [PATCH v2 2/4] iio: adc: add support for Allwinner SoCs ADC To: Quentin Schulz , jdelvare@suse.com, linux@roeck-us.net, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, maxime.ripard@free-electrons.com, wens@csie.org, lee.jones@linaro.org References: <1468576754-3273-1-git-send-email-quentin.schulz@free-electrons.com> <1468576754-3273-3-git-send-email-quentin.schulz@free-electrons.com> <578DE5C9.8070502@free-electrons.com> <26aa8f33-8525-6d82-ca17-b782c55c2c82@free-electrons.com> Cc: linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, thomas.petazzoni@free-electrons.com, antoine.tenart@free-electrons.com From: Jonathan Cameron Message-ID: Date: Sat, 23 Jul 2016 08:37:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <26aa8f33-8525-6d82-ca17-b782c55c2c82@free-electrons.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/07/16 14:15, Quentin Schulz wrote: > On 20/07/2016 16:57, Jonathan Cameron wrote: >> On 19/07/16 09:33, Quentin Schulz wrote: >>> On 18/07/2016 15:18, Jonathan Cameron wrote: >>>> On 15/07/16 10:59, Quentin Schulz wrote: > [...] >>>>> + enable_irq(info->temp_data_irq); >>>> Is this hardware spitting out extra irqs? If not, much better to just >>>> leave it enabled all the time and control whether it can occur or not >>>> by controlling the device state.. >>> >>> The temp_data_irq occurs every SUNXI_GPADC_TEMP_PERIOD(x) periods (in >>> the current state of the driver: 2s). What do you mean by controlling >>> the device state? Enabling or disabling the hardware part of the IP >>> responsible of getting the temperature >>> (SUNXI_GPADC_TP_TPR_TEMP_ENABLE(x) here)? >> Yes, or something along those lines if it wakes up fast enough. > > The ADC wakes up fast enough but resets its internal time clock (I don't > know if it's the right term to use). Note that the temperature interrupt > occurs by period of X seconds in this IP. > > This means that each time we disable the ADC on the hardware side, no > temperature interrupt will occur within the first X seconds. I don't > think this is what we want. I'm guessing X is non trivial ;) So fair enough. Could you add this justification as a comment in the driver somewhere so that people coming back to this in a few years time will know what the justification for this 'unusual' handling is. Thanks, Jonathan > > [...] > > Quentin > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >