Re: [BUG] i2c: acpi: Dell XPS 17 9720 ELAN 04F3:311C touchpad (VEN_04F3) needs 100 kHz like DLL0945

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Hi,

On Mon, Nov 09, 2026 at 08:57:13PM +0000, penhouse24@proton.me wrote:
> Hi Mika, 
> 
> Thank you for the response (I honestly wasn't expecting anyone to respond for this niche issue---so a welcome surprise). 
> 
> Yes my BIOS version (v1.41.0) is up to date. Currently, there are no updates available through Windows or from fwupd. I have received BIOS updates many times via Windows since purchasing this computer in 2022 and have had 0 change to this problem. 
> 
> For what it’s worth, the DSDT has a valid default ID. TPD0 starts with Name (ITPN, “DELL0AFF”), and _INI then overwrites it from the BIOS-provided TPHD variable, which yields “VEN_04F3”.
> 
> Please find attached the output of 'sudo dmidecode'. 
> 
> Thank you for helping me fix this. 

Can you try the below patch?

diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index 84841ed13487..bed9260056b3 100644
--- a/drivers/i2c/i2c-core-acpi.c
+++ b/drivers/i2c/i2c-core-acpi.c
@@ -7,6 +7,7 @@
 
 #include <linux/acpi.h>
 #include <linux/device.h>
+#include <linux/dmi.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/list.h>
@@ -356,6 +357,17 @@ static const struct acpi_device_id i2c_acpi_force_400khz_device_ids[] = {
 	{ }
 };
 
+static const struct dmi_system_id i2c_acpi_dell_xps_17_9720_dmi_ids[] = {
+	{
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "XPS 17 9720"),
+			DMI_MATCH(DMI_BIOS_VERSION, "1.41.0"),
+		},
+	},
+	{ }
+};
+
 static const struct acpi_device_id i2c_acpi_force_100khz_device_ids[] = {
 	/*
 	 * When a 400KHz freq is used on this model of ELAN touchpad in Linux,
@@ -377,6 +389,14 @@ static const struct acpi_device_id i2c_acpi_force_100khz_device_ids[] = {
 	{ .id = "ELAN0678" },
 	{ .id = "ELAN06FA" },
 	{ .id = "ELAN1300" },
+	{
+		/*
+		 * Some Dell XPS 17 9720 is not using standard ACPI IDs
+		 * so we need to match also via DMI strings.
+		 */
+		.id = "VEN_04F3",
+		.driver_data = (kernel_ulong_t)i2c_acpi_dell_xps_17_9720_dmi_ids,
+	},
 	{ }
 };
 
@@ -385,6 +405,7 @@ static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 {
 	struct i2c_acpi_lookup *lookup = data;
 	struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
+	const struct acpi_device_id *id;
 
 	if (!adev || i2c_acpi_do_lookup(adev, lookup))
 		return AE_OK;
@@ -398,7 +419,9 @@ static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 	if (acpi_match_device_ids(adev, i2c_acpi_force_400khz_device_ids) == 0)
 		lookup->force_speed = I2C_MAX_FAST_MODE_FREQ;
 
-	if (acpi_match_device_ids(adev, i2c_acpi_force_100khz_device_ids) == 0)
+	id = acpi_match_acpi_device(i2c_acpi_force_100khz_device_ids, adev);
+	if (id && (!id->driver_data ||
+		   dmi_check_system((const struct dmi_system_id *)id->driver_data)))
 		lookup->force_speed = I2C_MAX_STANDARD_MODE_FREQ;
 
 	return AE_OK;