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Subject: Re: [BUG] i2c-hid: ELAN Touchpad does not work on ASUS X580GD
To:     Jarkko Nikula <jarkko.nikula@linux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        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>,
        Jani Nikula <jani.nikula@intel.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Adrian Salido <salidoa@google.com>,
        Jason Gerecke <killertofu@gmail.com>,
        linux-input <linux-input@vger.kernel.org>,
        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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From:   Hans de Goede <hdegoede@redhat.com>
Message-ID: <9e49fc42-75be-3bd5-dfa4-9cc61348d501@redhat.com>
Date:   Fri, 18 May 2018 15:09:29 +0200
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Hi,

On 18-05-18 12:58, Jarkko Nikula wrote:
> On 05/18/2018 01:20 PM, Andy Shevchenko wrote:
>> On Fri, 2018-05-18 at 11:37 +0300, Andy Shevchenko wrote:
>>> On Fri, 2018-05-18 at 09:48 +0200, Hans de Goede wrote:
>>>
>>>
>>>> Could it be the i2c input clock definition in drivers/mfd/intel-
>>>> lpss-
>>>> pci.c
>>>> is also wrong for Apollo Lake (N3450) ?  There are lots of people
>>>> having
>>>> various issues with i2c attached touchpads on Apollo Lake devices,
>>>> this bug:
>>>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1728244
>>>>
>>>> Is sort of a collection bug for these. Various models laptops, lots
>>>> of
>>>> reporters. Note not sure thie is an i2c-designware issue, but it
>>>> would
>>>> be good to double check the input clock on Apollo Lake.
>>>>
>>>> I've checked the datasheet and the datasheet mentions 133MHz as
>>>> "serial input clk" in the lpio_bxt_regs Registers Summary, which is
>>>> also part of the LPSS, no clk is mentioned in the "Summary of
>>>> DW_apb_i2c_mem_map_DW_apb_i2c_addr_block1 Registers".
>>>
>>> The internal datasheet we have access to mentioned in this case for
>>> Broxton and Cannonlake together. So, your assumption might be quite
>>> close to the truth and the issue is inherited from Broxton.
>>>
>>
> Nope. The specification I have mention the I2C input clock in Broxton is fixed 133 MHz but in Cannon Lake it is derived through non-SW visible divider.
> 
>> Hans, can your reporters try the following patch? Depending on the
>> result I may send it out ASAP.
>>
>> --- a/drivers/mfd/intel-lpss-pci.c
>> +++ b/drivers/mfd/intel-lpss-pci.c
>> @@ -120,7 +120,7 @@ static struct property_entry apl_i2c_properties[] =
>> {
>>   };
>>   static const struct intel_lpss_platform_info apl_i2c_info = {
>> -       .clk_rate = 133000000,
>> +       .clk_rate = 216000000,
>>          .properties = apl_i2c_properties,
>>   };
>>
> Nack. The Apollo Lake HW here shows expected I2C bus clock on oscilloscope so it is indeed clocked at 133 MHz.

Ok, thank you for checking this.

Regards,

Hans