[PATCH] i2c: acpi: Add ELAN0662 to i2c_acpi_force_100khz_device_ids

[PATCH] i2c: acpi: Add ELAN0662 to i2c_acpi_force_100khz_device_ids

[Yuqi Xu]

The ELAN0662 touchpad (04F3:317C) in the Lenovo ThinkBook 14 G4+ ARA
(21D0) intermittently stutters and drops touches. libinput discards
invalid touch coordinates and logs (rate limited to five messages per
24 hours):

  libinput error: event6 - ELAN0662:00 04F3:317C Touchpad: kernel
  bug: Touch jump detected and discarded.

The ACPI DSDT describes the touchpad's I2cSerialBus resource on an
AMDI0010 controller with a connection speed of 0x00061A80 (400 kHz),
and the kernel does not lower it for this device, so the touchpad runs
at 400 kHz. This is the same issue previously fixed for ELAN06FA and
ELAN0678.

Forcing the bus to 100 kHz was tested with a DSDT override on the
affected machine, and the kernel confirmed the override:

  ACPI: Table Upgrade: override [DSDT-LENOVO-CB-01]

Before the change libinput discarded three touch jumps within about a
minute of touchpad use; after the change no touch jumps were logged
during more than an hour of normal use. The patch itself was not build
tested; the behaviour was validated through the ACPI table override
above.

Assisted-by: DeepSeek:deepseek-v4.1-flash
Signed-off-by: Yuqi Xu <xuyuqiabc@gmail.com>
---
 drivers/i2c/i2c-core-acpi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index 3af0e0551185..aae4f159955a 100644
--- a/drivers/i2c/i2c-core-acpi.c
+++ b/drivers/i2c/i2c-core-acpi.c
@@ -373,6 +373,7 @@ static const struct acpi_device_id i2c_acpi_force_100khz_device_ids[] = {
 	 */
 	{ "DELL0A86", 0 },
 	{ "DLL0945", 0 },
+	{ "ELAN0662", 0 },
 	{ "ELAN0678", 0 },
 	{ "ELAN06FA", 0 },
 	{ "ELAN1300", 0 },
-- 
2.55.0

Re: [PATCH] i2c: acpi: Add ELAN0662 to i2c_acpi_force_100khz_device_ids

[Mika Westerberg]

On Fri, Sep 18, 2026 at 01:41:09PM +0800, Yuqi Xu wrote:
> The ELAN0662 touchpad (04F3:317C) in the Lenovo ThinkBook 14 G4+ ARA
> (21D0) intermittently stutters and drops touches. libinput discards
> invalid touch coordinates and logs (rate limited to five messages per
> 24 hours):
> 
>   libinput error: event6 - ELAN0662:00 04F3:317C Touchpad: kernel
>   bug: Touch jump detected and discarded.
> 
> The ACPI DSDT describes the touchpad's I2cSerialBus resource on an
> AMDI0010 controller with a connection speed of 0x00061A80 (400 kHz),
> and the kernel does not lower it for this device, so the touchpad runs
> at 400 kHz. This is the same issue previously fixed for ELAN06FA and
> ELAN0678.
> 
> Forcing the bus to 100 kHz was tested with a DSDT override on the
> affected machine, and the kernel confirmed the override:
> 
>   ACPI: Table Upgrade: override [DSDT-LENOVO-CB-01]
> 
> Before the change libinput discarded three touch jumps within about a
> minute of touchpad use; after the change no touch jumps were logged
> during more than an hour of normal use. The patch itself was not build
> tested; the behaviour was validated through the ACPI table override
> above.
> 
> Assisted-by: DeepSeek:deepseek-v4.1-flash
> Signed-off-by: Yuqi Xu <xuyuqiabc@gmail.com>

Acked-by: Mika Westerberg (Intel) <westeri@kernel.org>