Re: [PATCH] Force ELAN06FA touchpad I2C bus freq to 100KHz

Wolfram Sang
2025-01-14T11:58:25Z

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On Mon, Jan 13, 2025 at 02:52:37PM -0500, Randolph Ha wrote:
> When a 400KHz freq is used on this model of ELAN touchpad in Linux,
> excessive smoothing (similar to when the touchpad's firmware detects
> a noisy signal) is sometimes applied. As some devices' (e.g, Lenovo
> V15 G4) ACPI tables specify a 400KHz frequency for this device and
> some I2C busses (e.g, Designware I2C) default to a 400KHz freq,
> force the speed to 100KHz as a workaround.
>
> For future investigation: This problem may be related to the default
> HCNT/LCNT values given by some busses' drivers, because they are not
> specified in the aforementioned devices' ACPI tables, and because
> the device works without issues on Windows at what is expected to be
> a 400KHz frequency. The root cause of the issue is not known.
>
> Signed-off-by: Randolph Ha <rha051117@gmail.com>
> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Applied to for-next, thanks!

Some comments for next contributions. Please send new patches always in
a new thread. It was a bit confusing here to find the latest one.

Also, while the code change looks easy, this is not a trivial change, so
trivial@ is not appropriate here. Trivial patches are more like typos or
whitespace fixes.

Nonetheless, thanks again for your efforts in timely debugging this!

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