From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756216AbcH2GSX (ORCPT ); Mon, 29 Aug 2016 02:18:23 -0400 Received: from mga03.intel.com ([134.134.136.65]:61820 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750730AbcH2GSW (ORCPT ); Mon, 29 Aug 2016 02:18:22 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,595,1464678000"; d="scan'208";a="1048525462" Subject: Re: [PATCH v1] i2c: designware: save the preset value of DW_IC_SDA_HOLD To: Andy Shevchenko , Zhuo-hao Lee , mika.westerberg@linux.intel.com, wsa@the-dreams.de, linux-i2c@vger.kernel.org References: <1472283570-31471-1-git-send-email-zhuo-hao.lee@intel.com> <1472387502.4887.321.camel@linux.intel.com> Cc: linux-kernel@vger.kernel.org From: Jarkko Nikula Message-ID: <70696be2-bead-9241-508d-dd1b02181766@linux.intel.com> Date: Mon, 29 Aug 2016 09:17:26 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.2.0 MIME-Version: 1.0 In-Reply-To: <1472387502.4887.321.camel@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/28/2016 03:31 PM, Andy Shevchenko wrote: > On Sat, 2016-08-27 at 15:39 +0800, Zhuo-hao Lee wrote: >> There are several ways to set the SDA hold time for i2c controller, >> including: Device Tree, built-in device properties and ACPI. However, >> if the SDA hold time is not specified by above method, we should >> read the value, where it is preset by firmware, and save it to >> sda_hold_time. This is needed because when i2c controller enters >> runtime suspend, the DW_IC_SDA_HOLD value will be reset to chipset >> default value. And during runtime resume, i2c_dw_init will be called >> to reconfigure i2c controller. If sda_hold_time is zero, the chipset >> default hold time will be used, that will be too short for some >> platforms. Therefore, to have a better tolerance, the DW_IC_SDA_HOLD >> value should be kept by sda_hold_time. > > Looks good to me. > Reviewed-by: Andy Shevchenko > Acked-by: Jarkko Nikula