Re: [BUG] i2c-hid: ELAN Touchpad does not work on ASUS X580GD

[Jarkko Nikula <jarkko.nikula@linux.intel.com>]

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.

-- 
Jarkko