From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15965C3A59E for ; Wed, 4 Sep 2019 05:54:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E670D23404 for ; Wed, 4 Sep 2019 05:54:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728551AbfIDFyL (ORCPT ); Wed, 4 Sep 2019 01:54:11 -0400 Received: from mga06.intel.com ([134.134.136.31]:57925 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725840AbfIDFyL (ORCPT ); Wed, 4 Sep 2019 01:54:11 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Sep 2019 22:54:10 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,465,1559545200"; d="scan'208";a="212262724" Received: from mylly.fi.intel.com (HELO [10.237.72.68]) ([10.237.72.68]) by fmsmga002.fm.intel.com with ESMTP; 03 Sep 2019 22:54:08 -0700 Subject: Re: Tweak I2C SDA hold time on GemniLake to make touchpad work To: Chris Chiu Cc: Mika Westerberg , Andy Shevchenko , lee.jones@linaro.org, Linux Kernel , Linux Upstreaming Team References: <20190903081858.GA2691@lahna.fi.intel.com> <3141a819-5964-4082-6f05-1926e16468b4@linux.intel.com> From: Jarkko Nikula Message-ID: <63364b2f-dc55-4fcb-5de5-d09c9622943a@linux.intel.com> Date: Wed, 4 Sep 2019 08:54:08 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/4/19 7:38 AM, Chris Chiu wrote: > On Tue, Sep 3, 2019 at 8:03 PM Jarkko Nikula > wrote: >> >> Hi Chris >> >> On 9/3/19 11:18 AM, Mika Westerberg wrote: >>> +Jarkko >>> >>> On Tue, Sep 03, 2019 at 04:10:27PM +0800, Chris Chiu wrote: >>>> Hi, >>>> >>>> We're working on the acer Gemnilake laptop TravelMate B118-M for >>>> touchpad not working issue. The touchpad fails to bring up and the >>>> i2c-hid ouput the message as follows >>>> [ 8.317293] i2c_hid i2c-ELAN0502:00: hid_descr_cmd failed >>>> We tried on latest linux kernel 5.3.0-rc6 and it reports the same. >>>> >>>> We then look into I2C signal level measurement to find out why. >>>> The following is the signal output from LA for the SCL/SDA. >>>> https://imgur.com/sKcpvdo >>>> The SCL frequency is ~400kHz from the SCL period, but the SDA >>>> transition is quite weird. Per the I2C spec, the data on the SDA line >>>> must be stable during the high period of the clock. The HIGH or LOW >>>> state of the data line can only change when the clock signal on the >>>> SCL line is LOW. The SDA period span across 2 SCL high, I think >>>> that's the reason why the I2C read the wrong data and fail to initialize. >>>> >>>> Thus, we treak the SDA hold time by the following modification. >>>> >>>> --- a/drivers/mfd/intel-lpss-pci.c >>>> +++ b/drivers/mfd/intel-lpss-pci.c >>>> @@ -97,7 +97,8 @@ static const struct intel_lpss_platform_info bxt_uart_info = { >>>> }; >>>> >>>> static struct property_entry bxt_i2c_properties[] = { >>>> - PROPERTY_ENTRY_U32("i2c-sda-hold-time-ns", 42), >>>> + PROPERTY_ENTRY_U32("i2c-sda-hold-time-ns", 230), >>>> PROPERTY_ENTRY_U32("i2c-sda-falling-time-ns", 171), >>>> PROPERTY_ENTRY_U32("i2c-scl-falling-time-ns", 208), >>>> { }, >>>> >>>> The reason why I choose sda hold time is by the Table 10 of >>>> https://www.nxp.com/docs/en/user-guide/UM10204.pdf, the device >>>> must provide a hold time at lease 300ns and and 42 here is relatively >>>> too small. The signal measurement result for the same pin on Windows >>>> is as follows. >>>> https://imgur.com/BtKUIZB >>>> Comparing to the same result running Linux >>>> https://imgur.com/N4fPTYN >>>> >>>> After applying the sda hold time tweak patch above, the touchpad can >>>> be correctly initialized and work. The LA signal is shown as down below. >>>> https://imgur.com/B3PmnIp >>>> >> Could you try does attached patch work for you? >> >> It's from last year for another related issue but there platform was >> actually Apollo Lake instead of Gemini Lake but anyway it was found out >> that Windows uses different timing parameters than Linux on Gemini Lake. >> >> I didn't take patch forward back then due known Gemini Lake machines >> were working with the Broxton I2C timing parameters but now it's time if >> attached patch fixes the issue on your machine. >> >> Patch is from top of v5.3-rc7 but should probably apply also to older >> kernels. >> >> -- >> Jarkko > > Thanks, Jarkko, the patche works on my acer laptops. > Thanks. I'll send the patch out with Cc'ing you. I took the freedom to add your Tested-by tag if you don't mind :-) -- Jarkko