Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [BUG] i2c-hid: ELAN Touchpad does not work on ASUS X580GD
To:     Chris Chiu <chiu@endlessm.com>, Daniel Drake <drake@endlessm.com>
Cc:     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>
References: <CAPpJ_ed-JPOzQPtyCdH4_C7dzEeM3fznus8XDuaojaiM_4nFpw@mail.gmail.com>
 <CAB4CAwcKu88xP0R9P-3csd6SE2fZ-Vb6OrQD9AmBDh6p77VFDQ@mail.gmail.com>
 <a9e1f1cb-b823-8690-930f-f7346798341a@linux.intel.com>
 <CAD8Lp46b+-B=xqSAqB+zV4xF6SRUGs46FkydS37UEuqav_jNog@mail.gmail.com>
 <CAB4CAwd0tN7CaS7YZCo3TZH-DPxt0x6wxyO23v7aBW9MOCtHCw@mail.gmail.com>
From:   Jarkko Nikula <jarkko.nikula@linux.intel.com>
Message-ID: <c1343704-6b1a-14b5-3942-a8a33f73feee@linux.intel.com>
Date:   Mon, 14 May 2018 17:20:22 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.7.0
MIME-Version: 1.0
In-Reply-To: <CAB4CAwd0tN7CaS7YZCo3TZH-DPxt0x6wxyO23v7aBW9MOCtHCw@mail.gmail.com>
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

On 05/10/2018 03:03 PM, Chris Chiu wrote:
> Report from guys who can access scope. If i2c-sda-falling-time-ns=400ns
> , HCNT increase to 117, the SCL high duration is 576ns as follows
> https://pasteboard.co/HkwERvP.png
> 
> The original SCL high duration (HCNT = 105, 120MHz) is as follows
> https://pasteboard.co/HkwFxgY.png
> 
> So the HCNT does affect but per this HCNT/LCNT value, just not 400kHz
> as expected. Any suggestion?
> 
Thanks for measurements. I was sidetracked last week so I don't have yet 
explanation why signals run faster than expected :-(

Using 120 MHz SPT I2C clocks in commit b418bbff36dd ("mfd: intel-lpss: 
Add Intel Cannonlake PCI IDs") is clearly wrong but before going to 133 
MHz (which work for you but still runs too fast) I would like to find 
explanation why it appears to be much higher.

-- 
Jarkko