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Subject: Re: [BUG] i2c-hid: ELAN Touchpad does not work on ASUS X580GD
From: Jarkko Nikula <jarkko.nikula@linux.intel.com>
To: Chris Chiu <chiu@endlessm.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>,
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        linux-input <linux-input@vger.kernel.org>,
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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