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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 36FCAC3A59E for ; Wed, 4 Sep 2019 04:38:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 04C0A22CED for ; Wed, 4 Sep 2019 04:38:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=endlessm-com.20150623.gappssmtp.com header.i=@endlessm-com.20150623.gappssmtp.com header.b="nNUzE22s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728215AbfIDEih (ORCPT ); Wed, 4 Sep 2019 00:38:37 -0400 Received: from mail-qt1-f182.google.com ([209.85.160.182]:41387 "EHLO mail-qt1-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725840AbfIDEig (ORCPT ); Wed, 4 Sep 2019 00:38:36 -0400 Received: by mail-qt1-f182.google.com with SMTP id j10so5273704qtp.8 for ; Tue, 03 Sep 2019 21:38:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=endlessm-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=rCfo8ZTPLFD1J9LanJqx/ih06mAfCjEXW/qtymlzmaY=; b=nNUzE22szLB6fIHBMR61HcFOyBi2VxuEnTbkYKcFzTfAR0nkrN45m6Of3tnpFA2oyx P1fi4etH/iQsP64d4b0YNZlnLtUlvmEHAgNlv66WbzKe+8hmp7jUpcRvHOuDj5i0FLU3 A3HVwuRPEMedPMCsVK5PH0596ZxTw9AkeUxaZOlFEBRtYx83g+ZOEE/OV5cRlC3r4r7a gf8CohZBRIO4k48aQnrWZDr/m9fQ3BsOpyj4KcC0VmY768nqdBJtX/njhT0kB4h21Due SxBimvqXPlVileAF76Tzhf6zGehsrzX/zAWBFjDRoPinSnt8+/kxRe3juVV0snbQlQ8Y pcOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rCfo8ZTPLFD1J9LanJqx/ih06mAfCjEXW/qtymlzmaY=; b=L00wLmqASJbeQSi46pKpQjrNi7AYbDFElJ38xQPNFFsT6ep7+Zd9xSswoWbmNaf7iO zHaD5TqpSiKIAtbyHLcCO9xS/zePdlJUEpYEsdCkYyuB3W8OfZfBnXFv3LBEUwt1W30h OKb2PFvgm6b7YMGnttKGhKyl1lYf9X8iXbImXsdCjV+48qiWoHB5xyhuDxv1rmYec6qE QKqIlnUnNraXVcdlbz/TS9ByUPp/9grvfvp1ytqRh5SZmkwowDmHscCqVX4QWnOWYExT UnWkfzwhjUR48bI1v+9GFlTSGic7vtee8IPdOnpHC8dkCy7AkIoznsICaBOHgu+E4D7q MLYA== X-Gm-Message-State: APjAAAXIpq5/ycUyWlUD7+58+ZwfV9mJcaSNppuj09bXbjKJSAfZQhHb oXpMCiwR7E7eNLdIZkBS+fiaLhIRcZnYzSsvmAmPMQ== X-Google-Smtp-Source: APXvYqyGEOXLOXrHz31XbbkOyu/PhaDVQ5axvbUz3OqstIKTzlq16n68flaEzNvHDLw7Qn3j0Twu0+XOyVZW+dXa+og= X-Received: by 2002:ac8:7959:: with SMTP id r25mr37347795qtt.208.1567571915575; Tue, 03 Sep 2019 21:38:35 -0700 (PDT) MIME-Version: 1.0 References: <20190903081858.GA2691@lahna.fi.intel.com> <3141a819-5964-4082-6f05-1926e16468b4@linux.intel.com> In-Reply-To: <3141a819-5964-4082-6f05-1926e16468b4@linux.intel.com> From: Chris Chiu Date: Wed, 4 Sep 2019 12:38:24 +0800 Message-ID: Subject: Re: Tweak I2C SDA hold time on GemniLake to make touchpad work To: Jarkko Nikula Cc: Mika Westerberg , Andy Shevchenko , lee.jones@linaro.org, Linux Kernel , Linux Upstreaming Team Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Chris