Re: [PATCH] i2c: acpi: Add ELAN0678 to i2c_acpi_force_100khz_device_ids

Re: [PATCH] i2c: acpi: Add ELAN0678 to i2c_acpi_force_100khz_device_ids

[Odoben]

Hi,

I have what appears to be the same issue on a ThinkPad X13 Gen 2 with 
Intel i5-1145G7, but with ACPI HID ELAN0676 instead of ELAN0678.

The touchpad is:

ELAN0676:00 04F3:3195 Touchpad

libinput reports:

Id: i2c:04f3:3195

dmesg shows:

i2c_designware.0 -> i2c-ELAN0676:00 -> hid-multitouch

The ACPI table contains:

Package (0x06)
{
0x04F3,
0x3195,
0x15,
One,
One,
"ELAN0676"
}

and the surrounding firmware logic maps the fifth field to speed:

Local5 == Zero -> SPED = 0x000186A0 = 100 kHz
Local5 == One -> SPED = 0x00061A80 = 400 kHz

So this machine also configures the 04F3:3195 ELAN touchpad at 400 
kHz. The symptom is very frequent rubbery/sluggish pointer movement, 
consistent with the excessive smoothing described for ELAN0678.

Would it make sense to include ELAN0676 in the 
same i2c_acpi_force_100khz_device_ids quirk?

Thanks,
Odoben

On 2026-05-04 11:19, Wolfram Sang wrote:
> On Sat, Apr 18, 2026 at 07:37:19AM +0200, Niels Franke wrote:
>> The ELAN0678 touchpad (04F3:3195) found in the Lenovo ThinkPad X13
>> exhibits excessive smoothing when the I2C bus runs at 400KHz, making
>> the touchpad feel sluggish when plugged into AC power. This is the
>> same issue previously fixed for ELAN06FA.
>>
>> The device's ACPI table (Lenovo TP-R22) specifies 0x00061A80 (400KHz)
>> for the I2cSerialBusV2 descriptor. Forcing the bus to 100KHz eliminates
>> the sluggish behavior.
>>
>> Signed-off-by: Niels Franke <nielsfranke@gmail.com>
> Kept the sorting (alphanumeric) and applied to for-current, thanks!
>

Re: [PATCH] i2c: acpi: Add ELAN0678 to i2c_acpi_force_100khz_device_ids

[Wolfram Sang]

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Hi,

> I have what appears to be the same issue on a ThinkPad X13 Gen 2 with
> Intel i5-1145G7, but with ACPI HID ELAN0676 instead of ELAN0678.

...

> Would it make sense to include ELAN0676 in the
> same i2c_acpi_force_100khz_device_ids quirk?

Sounds much like it. Can you create such a patch? Or can you test such
a patch if we provide you one?

Happy hacking,

   Wolfram


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Re: [PATCH] i2c: acpi: Add ELAN0678 to i2c_acpi_force_100khz_device_ids

[Mika Westerberg]

Hi,

On Tue, May 12, 2026 at 11:36:26PM +0200, Odoben wrote:
> Hi,
> 
> I have what appears to be the same issue on a ThinkPad X13 Gen 2 with
> Intel i5-1145G7, but with ACPI HID ELAN0676 instead of ELAN0678.
> 
> The touchpad is:
> 
> ELAN0676:00 04F3:3195 Touchpad
> 
> libinput reports:
> 
> Id: i2c:04f3:3195
> 
> dmesg shows:
> 
> i2c_designware.0 -> i2c-ELAN0676:00 -> hid-multitouch
> 
> The ACPI table contains:
> 
> Package (0x06)
> {
> 0x04F3,
> 0x3195,
> 0x15,
> One,
> One,
> "ELAN0676"
> }
> 
> and the surrounding firmware logic maps the fifth field to speed:
> 
> Local5 == Zero -> SPED = 0x000186A0 = 100 kHz
> Local5 == One -> SPED = 0x00061A80 = 400 kHz
> 
> So this machine also configures the 04F3:3195 ELAN touchpad at 400 kHz. The
> symptom is very frequent rubbery/sluggish pointer movement, consistent with
> the excessive smoothing described for ELAN0678.
> 
> Would it make sense to include ELAN0676 in the
> same i2c_acpi_force_100khz_device_ids quirk?

Did you try 100Hz and it made the problem go away? In that case yes it
makes sense to add the quirk.