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From:   Chris Chiu <chiu@endlessm.com>
Date:   Thu, 17 May 2018 17:05:38 +0800
Message-ID: <CAB4CAwdEYJncAxD30UxbFcdz57+AoJnda_L9X3kR6vs=z-dmdQ@mail.gmail.com>
Subject: Re: [BUG] i2c-hid: ELAN Touchpad does not work on ASUS X580GD
To:     Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc:     Daniel Drake <drake@endlessm.com>,
        Jian-Hong Pan <jian-hong@endlessm.com>,
        Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Jani Nikula <jani.nikula@intel.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Adrian Salido <salidoa@google.com>,
        Jason Gerecke <killertofu@gmail.com>,
        linux-input <linux-input@vger.kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Wolfram Sang <wsa@the-dreams.de>, linux-i2c@vger.kernel.org,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Linux Upstreaming Team <linux@endlessm.com>
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On Thu, May 17, 2018 at 3:48 PM, Jarkko Nikula
<jarkko.nikula@linux.intel.com> wrote:
> Hi
>
> On 05/15/2018 01:20 PM, Jarkko Nikula wrote:
>>
>> On 05/15/2018 06:22 AM, Chris Chiu wrote:
>>>
>>> What if I change the 120MHz to 180MHz and then make sure that the I2C
>>> operates
>>> in target FS mode frequency 400kHz via scope? Would there be any side
>>> effect?
>>> Maybe some other busses frequency could be also affected and causing some
>>> other
>>> component malfunction?
>>>
>> Should be safe. It is only clock rate information when registering a fixed
>> clock with known rate in intel-lpss.c and i2c-designware uses that info when
>> calculating the timing parameters. I.e. it doesn't change any internal
>> clocks.
>>
>> I'm trying to find a contact who can confirm what is the expected rate of
>> I2C input clock and is it common to all Cannon Lake HW.
>>
> I got confirmation that input clock is actually even higher 216 Mhz.
>
> While checking does it cover all of those CNL CNL-LP and CNL-H PCI IDs may I
> add your Jian-Hong, Chris and Daniel email addresses to Repored-by tags in a
> fix patch?
>
> --
> Jarkko

No problem. Thanks