From mboxrd@z Thu Jan 1 00:00:00 1970 From: chin.yew.tan@intel.com Subject: [PATCH v2] Set sda-hold-time based on ACPI *CNT value Date: Tue, 14 Feb 2017 13:54:00 +0800 Message-ID: <1487051641-31927-1-git-send-email-chin.yew.tan@intel.com> Return-path: Received: from mga06.intel.com ([134.134.136.31]:10565 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750749AbdBNFyJ (ORCPT ); Tue, 14 Feb 2017 00:54:09 -0500 Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: jarkko.nikula@linux.intel.com, andriy.shevchenko@linux.intel.com, mika.westerberg@linux.intel.com Cc: linux-i2c@vger.kernel.org From: Tan Chin Yew For I2c to operate correctly under all speed mode, sda-hold-time need to be perfectly tuned. However, sda-hold-time is precalculated according to circuit parameter which make it platform-specific. In order to get accurate sda-hold-time for all platforms, pretuned sda-hold-time for particular platform is stored in ACPI table and driver to load the sda holding time from ACPI table. This patch read the I2c sda-hold-time from ACPI table and assigned the suitable hold time based on the i2c clock frequency. Tested on Intel Apollo Lake. Changes in V2: - The code is realigned according to suggestion. - "case 400000:" is added on top of "default:" for readability. Tan Chin Yew (1): i2c: designware: Get selected speed mode sda-hold-time via ACPI drivers/i2c/busses/i2c-designware-platdrv.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) -- 1.9.1