From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from www381.your-server.de ([78.46.137.84]:55943 "EHLO www381.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751209AbcFVICH (ORCPT ); Wed, 22 Jun 2016 04:02:07 -0400 Subject: Re: [PATCH v3] iio: temperature: add support for Maxim thermocouple chips To: Jonathan Cameron , Matt Ranostay References: <1464572270-29154-1-git-send-email-mranostay@gmail.com> <6e79df7d-4ac1-3a44-e303-af858f30e161@kernel.org> <77a1a974-2636-878b-742c-d624cc5fdc58@kernel.org> Cc: linux-iio@vger.kernel.org, Marek Vasut , Matt Porter , Daniel Baluta , Peter Meerwald From: Lars-Peter Clausen Message-ID: <576A45FA.4020708@metafoo.de> Date: Wed, 22 Jun 2016 10:02:02 +0200 MIME-Version: 1.0 In-Reply-To: <77a1a974-2636-878b-742c-d624cc5fdc58@kernel.org> Content-Type: text/plain; charset=windows-1252 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 06/11/2016 06:48 PM, Jonathan Cameron wrote: > On 03/06/16 13:33, Jonathan Cameron wrote: >> On 30/05/16 02:37, Matt Ranostay wrote: >>> Add initial driver support for MAX6675, and MAX31885 thermocouple chips. >>> >>> Cc: Marek Vasut >>> Cc: Matt Porter >>> Signed-off-by: Matt Ranostay >> I'm going to let this sit for a sort while as I'd like some discussion >> of the invalidate buffer bit. >> >> Cc'd a few more people for views. > Hmm. Deadly silence. > > Daniel, Lars, Peter - this is a fairly fundamental abi question. > > What do we do to signify an 'invalid reading' in the buffer. > > Here the part is driven by a software trigger - and if we skip > a reading we are obviously out of sync. > > Old and nasty trick we used in some (possibly only one) > early driver was to set an invalid state for these cases. > > Anyone have a better idea? Ideally the driver would leave the data including the status bit intact and not replace it with a magic constant that way an application that is aware of the way the chip behaves could handle that.