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

[Jarkko Nikula]

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