From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Subject: Re: [BUG] i2c-hid: ELAN Touchpad does not work on ASUS X580GD
Date: Mon, 14 May 2018 17:20:22 +0300
Message-ID: <c1343704-6b1a-14b5-3942-a8a33f73feee@linux.intel.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>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <CAB4CAwd0tN7CaS7YZCo3TZH-DPxt0x6wxyO23v7aBW9MOCtHCw@mail.gmail.com>
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
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>
List-Id: linux-i2c@vger.kernel.org

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