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=-0.7 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 A9BCCC3A5A7 for ; Wed, 4 Sep 2019 06:24:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A17923402 for ; Wed, 4 Sep 2019 06:24:39 +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="sw34W2ei" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728797AbfIDGYi (ORCPT ); Wed, 4 Sep 2019 02:24:38 -0400 Received: from mail-qk1-f170.google.com ([209.85.222.170]:39197 "EHLO mail-qk1-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728108AbfIDGYi (ORCPT ); Wed, 4 Sep 2019 02:24:38 -0400 Received: by mail-qk1-f170.google.com with SMTP id 4so18582464qki.6 for ; Tue, 03 Sep 2019 23:24:37 -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=Di+GnDQ2TnjFeODH4tBfbLUz3tcQ/aVDZSgnwbe0+G4=; b=sw34W2eiN25sNXFeN8XcPZRfTjzJ9WiqbXI5QElU4GEHV0DY73/iysR6tIrZ5bj+ru N1q/jf5kMqw1WKASyIXUaNZmXjxynGDYh2Ps/g/K65gB3aoqH0etGpva9cEuTEZ9yAmL NPOFGy1sTDIIhwkCChDz+AZG+gQs2aoBKoC9JPUXzhDVN9R665r3rFtmQAALZfJcG7Qr /A0utUCvrMzmh5iGkW4tB+Rp0DujmxCblXA6pAePmnQUNM7SdsoWZEmv4/fWk3qK933a bxA5GdJt2LonHiE+xKiv16/eHTalLMFJryARg1fN1GCrBkj/NmB1vVbHQuY2q/MMXd5m pBMQ== 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=Di+GnDQ2TnjFeODH4tBfbLUz3tcQ/aVDZSgnwbe0+G4=; b=DWNQh+7eTs0nsEKzTFYfRPKdFfW6h0cMB+l1mGJbSiHosqGDUgUUrE9hE1IzOBpBrK IjCWy90BE5v8zWfQbzJSg/Q9EwFwqXBhRuWYCmyEtfKc3VqBQkoBrTP+lz0Dvs3WssmE dj36lIVpPjT1K+HyPxMq/5gFWxGNEyXbFesIYOfL+h5pXLVh4qhRvfMqxMhIdGReNv39 aIStRJqqxLMTEHDWtJwzsVDFGUW67FRXoAC6GIMJG+DkQHITcIkclA/WJNFxEu43xyEC /xC1N57j3P8R4n+smtM7/N0WiB93tMJHKHxd73qsvZc4dQNSrvJZQkeYDrX5PZ9tm/Wb iUQQ== X-Gm-Message-State: APjAAAVunWUnEKhvR3Q7G256ItIVZ/YlCVqPNjQXp2hTFszabOKcx2wT buPBXxUbcWGsYZRyzijD0CWHhFkwXYapXWI7VmspqQ== X-Google-Smtp-Source: APXvYqxS1H9FjbQL3VVWe5xB1by8z85l6KZ7J60TlCoh93QflHXIg7dBFhDVhv8EoQH7f7qbB5SuHzjqsX9n1naG3xo= X-Received: by 2002:a05:620a:5ad:: with SMTP id q13mr20244042qkq.297.1567578276980; Tue, 03 Sep 2019 23:24:36 -0700 (PDT) MIME-Version: 1.0 References: <20190903081858.GA2691@lahna.fi.intel.com> <3141a819-5964-4082-6f05-1926e16468b4@linux.intel.com> <63364b2f-dc55-4fcb-5de5-d09c9622943a@linux.intel.com> In-Reply-To: <63364b2f-dc55-4fcb-5de5-d09c9622943a@linux.intel.com> From: Chris Chiu Date: Wed, 4 Sep 2019 14:24:26 +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 Wed, Sep 4, 2019 at 1:54 PM Jarkko Nikula wrote: > > 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 No problem. Thanks