[PATCH] i2c: acpi: Force Dell XPS 17 9720 touchpad to 100 kHz

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

The Dell XPS 17 9720 touchpad has the same lagging issue as with others
when run at 400 kHz as the ACPI tables describe. This particular system
does not use standard ACPI ID but it seems to use "Windows Device ID"
VEN_04F3 for whatever reason. Add this one to the 100 kHz quirk list as
well but since this is not a standard ACPI ID match it also via DMI
strings just to be on the safe side.

Reported-by: penhouse24@proton.me
Link: https://lore.kernel.org/linux-i2c/20261109104542.GL176724@black.igk.intel.com/
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/i2c/i2c-core-acpi.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index 84841ed13487..98a8d63e3fb8 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 +357,16 @@ 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"),
+		},
+	},
+	{ }
+};
+
 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 +388,14 @@ static const struct acpi_device_id i2c_acpi_force_100khz_device_ids[] = {
 	{ .id = "ELAN0678" },
 	{ .id = "ELAN06FA" },
 	{ .id = "ELAN1300" },
+	{
+		/*
+		 * Some Dell XPS 17 9720 systems do not use 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 +404,7 @@ 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 +418,9 @@ 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;
-- 
2.53.0