From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756805Ab3KYOyk (ORCPT ); Mon, 25 Nov 2013 09:54:40 -0500 Received: from mout.gmx.net ([212.227.15.19]:49674 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756617Ab3KYOyi (ORCPT ); Mon, 25 Nov 2013 09:54:38 -0500 Message-ID: <529364AC.8000305@gmx.de> Date: Mon, 25 Nov 2013 15:54:36 +0100 From: Michael Lawnick User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20131118 Thunderbird/17.0.11 MIME-Version: 1.0 To: Mike Looijmans CC: Wolfram Sang , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] i2c-mux-pca954x: Disable mux after 200ms timeout References: <1385387037-3710-1-git-send-email-mike.looijmans@topic.nl> In-Reply-To: <1385387037-3710-1-git-send-email-mike.looijmans@topic.nl> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K0:lG3Blr1Mgzr4m02fu7WrB/pj56ZJtQDHcFHxHlt5hBfcOITzRBw ekSFusVHXtb3HMS1O54dXYapilOmB2Nsb3RKJF+PNTwYJTplhkhY8AiBmuz43FX7nF15/pG zEGSpeYFOe+b8IJV/VALKXMdc+Zx9PDsyhhymDhwbSW6PvFbA9GyRKPA+Fp+Y2MkcISIx2p 5YDpia0nH17e4mojIJrQA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Am 25.11.2013 14:43, schrieb Mike Looijmans: > Leaving the mux enabled causes needless I2C traffic on the downstream > bus. De-selecting after every request causes excess I2C traffic and > switching. > > This patch implements a hybrid solution: After 200ms of inactivity, > the mux is disabled. ... Have you checked against behavior on cascaded muxes? At least your desired timing will not look as expected. 200 ms: disable mux1 201 ms: enable mux1 - disable mux2 202 ms: enable mux2 - disable mux3 401 ms: disable mux1 402 ms: enable mux1 - disable mux2 602 ms: disable mux1 And on full second temperature sensor behind mux3 is read again ... KR Michael