i2c: acpi: Add VEN_04F3 to i2c_acpi_force_100khz_device_ids

[PATCH] i2c: acpi: Add VEN_04F3 to i2c_acpi_force_100khz_device_ids

Posted by Jacob Bazata 5 days, 21 hours ago

This model trackpad (04F3:32AA), found on various Dell XPS models
from 2023 including XPS 9500, 9510, 9520 and 9530 is well documented to,
at random, exhibit excessive smoothing with no obvious cause, similar
to other trackpad devices listed in the i2c_acpi_force_100khz_device
_ids struct.

Forcing the bus to 100KHz eliminates this behavior.

Signed-off-by: Jacob Bazata <jacobbazata@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 28c0e4884..512ebdfcc 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[] = {
 	{ "DLL0945", 0 },
 	{ "ELAN0678", 0 },
 	{ "ELAN06FA", 0 },
+	{ "VEN_04F3", 0 },
 	{}
 };
 
-- 
2.54.0

Re: [PATCH] i2c: acpi: Add VEN_04F3 to i2c_acpi_force_100khz_device_ids

Posted by Mika Westerberg 5 days, 16 hours ago

Hi,

On Tue, May 19, 2026 at 01:24:24AM -0400, Jacob Bazata wrote:
> This model trackpad (04F3:32AA), found on various Dell XPS models
> from 2023 including XPS 9500, 9510, 9520 and 9530 is well documented to,
> at random, exhibit excessive smoothing with no obvious cause, similar
> to other trackpad devices listed in the i2c_acpi_force_100khz_device
> _ids struct.
> 
> Forcing the bus to 100KHz eliminates this behavior.
> 
> Signed-off-by: Jacob Bazata <jacobbazata@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 28c0e4884..512ebdfcc 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[] = {
>  	{ "DLL0945", 0 },
>  	{ "ELAN0678", 0 },
>  	{ "ELAN06FA", 0 },
> +	{ "VEN_04F3", 0 },

This is interesting ACPI ID. Adding Andy just in case he has any comments
on it.

I'm fine with this.

>  	{}
>  };
>  
> -- 
> 2.54.0

Re: [PATCH] i2c: acpi: Add VEN_04F3 to i2c_acpi_force_100khz_device_ids

Posted by Andy Shevchenko 5 days, 15 hours ago

On Tue, May 19, 2026 at 12:05:29PM +0200, Mika Westerberg wrote:
> On Tue, May 19, 2026 at 01:24:24AM -0400, Jacob Bazata wrote:
> > This model trackpad (04F3:32AA), found on various Dell XPS models
> > from 2023 including XPS 9500, 9510, 9520 and 9530 is well documented to,
> > at random, exhibit excessive smoothing with no obvious cause, similar
> > to other trackpad devices listed in the i2c_acpi_force_100khz_device
> > _ids struct.
> > 
> > Forcing the bus to 100KHz eliminates this behavior.

...

> > +	{ "VEN_04F3", 0 },
> 
> This is interesting ACPI ID. Adding Andy just in case he has any comments
> on it.

Yes, it's simply bogus and not following the ACPI specification [0]. We might
add the bogus IDs, but that has to be justified in the commit message:

- Is the device available on a wild market?
- If no, drop the patch, fix the firmware (I'm here to help with ACPI process bits)
- If yes, provide the Device name, model, year, et cetera to unique distinguish it,
  provide an excerpt from DSDT to show how this device is described there
- Also browse the MS catalog [1], duckduckgo, google for the ID to see if it
appears in some respectful sources
- Additionally, try to submit a bug report to the vendor of the device to point
out that this is bogus ID and must be fixed  (in a new BIOSes)

The more information you find and provide the better. (But distinguish the
important from secondary info,)

[0]: https://uefi.org/specs/ACPI/6.6/06_Device_Configuration.html#hid-hardware-id
[1]: https://www.catalog.update.microsoft.com/Search.aspx?q=ven_04f3

-- 
With Best Regards,
Andy Shevchenko