From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756095AbbLQC45 (ORCPT ); Wed, 16 Dec 2015 21:56:57 -0500 Received: from mail-lf0-f42.google.com ([209.85.215.42]:33935 "EHLO mail-lf0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755115AbbLQC4z (ORCPT ); Wed, 16 Dec 2015 21:56:55 -0500 MIME-Version: 1.0 In-Reply-To: <1450319025-19120-1-git-send-email-Suravee.Suthikulpanit@amd.com> References: <1450319025-19120-1-git-send-email-Suravee.Suthikulpanit@amd.com> Date: Wed, 16 Dec 2015 18:56:54 -0800 Message-ID: Subject: Re: [PATCH v2] i2c: designware: Do not require clock when SSCN and FFCN are provided From: Loc Ho To: Suravee Suthikulpanit Cc: Mika Westerberg , wsa@the-dreams.de, jarkko.nikula@linux.intel.com, andriy.shevchenko@linux.intel.com, Ken Xue , linux-i2c@vger.kernel.org, linux-acpi@vger.kernel.org, Linux Kernel Mailing List 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, > The current driver uses input clock source frequency to calculate > values for [SS|FS]_[HC|LC] registers. However, when booting ACPI, we do not > currently have a good way to provide the frequency information. > Instead, we can leverage the SSCN and FFCN ACPI methods, which can be used > to directly provide these values. So, the clock information should > no longer be required during probing. > > However, since clk can be invalid, additional checks must be done where > we are making use of it. > > Signed-off-by: Suravee Suthikulpanit > --- > > Note: This has been tested on AMD Seattle RevB for both DT and ACPI. Tested on X-Gene hardware also. -Loc