From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH v1] i2c: designware: save the preset value of DW_IC_SDA_HOLD Date: Thu, 8 Sep 2016 22:18:51 +0200 Message-ID: <20160908201850.GA3166@katana> References: <1472283570-31471-1-git-send-email-zhuo-hao.lee@intel.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="3MwIy2ne0vdjdPXF" Return-path: Received: from sauhun.de ([89.238.76.85]:50167 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754584AbcIHUTD (ORCPT ); Thu, 8 Sep 2016 16:19:03 -0400 Content-Disposition: inline In-Reply-To: <1472283570-31471-1-git-send-email-zhuo-hao.lee@intel.com> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Zhuo-hao Lee Cc: jarkko.nikula@linux.intel.com, andriy.shevchenko@linux.intel.com, mika.westerberg@linux.intel.com, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org --3MwIy2ne0vdjdPXF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Aug 27, 2016 at 03:39:30PM +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. >=20 > Signed-off-by: Zhuo-hao Lee Applied to for-current, thanks! --3MwIy2ne0vdjdPXF Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJX0ceqAAoJEBQN5MwUoCm2fZMQAKSUpaWvPIiUlP4nmnh1or+c w/YflOrnwovTgfoy3UxPao5RnxhTx9WCgF/JDzFQyQ5pzg7zwFA1sN4e6P2XQnDi uhGpLEauJbWYweqlDb/l0+NUouP24+jLCoOokpK3fiuxutFAiXj9uTIDu7gn1ZAL pu/IvLreb11/0n0uTa0LX3GkFAYermhLRJ6QaGOlyV/Oz62VTHaq3JID+T+Kan5P 6vekOK52SGG37e58j4v0MO8G0H1OMnXu2LP+nNou7DQHsuZi5UpjceC5rWwhPtVQ 1YMkbKnNybqXS2s8bhJsaXBgJx4BYwo2fKGnY/hJekWshOQZ13YKvFrMvKNIUucu RrxLSPfoCDIs2fRwwUolNEu2nF/0wmH28Bmd+iN3Qa/vXHv39d86hCJ3JnGUGv20 R5AQooCJmQpFDcFI7S6NtI+Jl6bW6qghuREVSFBv6YKlxO1iKMUi6zqR2vVqUZz2 NoXgh+LVK61WY4Ivpj2OdentpfjqkvFVWGvCUPsxk9+Qt7M06HN5NlnxK74U4NSz kOEfo2T7cvdYE+RqaoY85cnh9XB4URbdPezRaubMbhr9WJqKedMnI5t7VRwrV0ZO qJXnmpKcw9xezJxPRt9vogUBZrMPRJ6buAX8MDon5FhboA7UsQUFjWgNud/vbn8o EN7JqVp8xUHDJFL3nNPO =UKOp -----END PGP SIGNATURE----- --3MwIy2ne0vdjdPXF--