Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933212AbaLBNar (ORCPT ); Tue, 2 Dec 2014 08:30:47 -0500 Received: from mail-la0-f48.google.com ([209.85.215.48]:59905 "EHLO mail-la0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932853AbaLBNam (ORCPT ); Tue, 2 Dec 2014 08:30:42 -0500 MIME-Version: 1.0 In-Reply-To: <20141202131611.GC4072@katana> References: <1417514749-24319-1-git-send-email-harinik@xilinx.com> <1417514749-24319-4-git-send-email-harinik@xilinx.com> <20141202111907.GC23671@leverpostej> <20141202125203.GA4072@katana> <20141202131611.GC4072@katana> Date: Tue, 2 Dec 2014 19:00:40 +0530 Message-ID: Subject: Re: [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C From: Harini Katakam To: Wolfram Sang Cc: Mark Rutland , "grant.likely@linaro.org" , "robh+dt@kernel.org" , Pawel Moll , "ijc+devicetree@hellion.org.uk" , "galak@codeaurora.org" , "michal.simek@xilinx.com" , "soren.brinkmann@xilinx.com" , "linux-arm-kernel@lists.infradead.org" , "linux-i2c@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , "vishnum@xilinx.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Tue, Dec 2, 2014 at 6:46 PM, Wolfram Sang wrote: > >> But given the bugs, it will be useful to just disable it if the system doesn't >> require repeated start. > > What do you do when disable repeated start? Sending STOP and START? If > so, this is really something different than repeated start. By using > I2C_FUNC_I2C a user expects repeated start, so if the HW does not > support it, we should say so and don't try to emulate it with something > different. > Yes, we send stop. Using repeated start, when number of messages passed > 1, HOLD bit is set by the driver. This is an indication to the controller not to send a STOP. If we disable repeated start, the driver will not set HOLD bit. All the messages are sent but with START and a STOP for each of them. Regards, Harini -- 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/