platform/x86: touchscreen_dmi: Allow partial (prefix) matches for ACP…

…I names

commit dbcbfd6 upstream.

On some devices the ACPI name of the touchscreen is e.g. either
MSSL1680:00 or MSSL1680:01 depending on the BIOS version.

This happens for example on the "Chuwi Hi8 Air" tablet where the initial
commit's ts_data uses "MSSL1680:00" but the tablets from the github issue
and linux-hardware.org probe linked below both use "MSSL1680:01".

Replace the strcmp() match on ts_data->acpi_name with a strstarts()
check to allow using a partial match on just the ACPI HID of "MSSL1680"
and change the ts_data->acpi_name for the "Chuwi Hi8 Air" accordingly
to fix the touchscreen not working on models where it is "MSSL1680:01".

Note this drops the length check for I2C_NAME_SIZE. This never was
necessary since the ACPI names used are never more then 11 chars and
I2C_NAME_SIZE is 20 so the replaced strncmp() would always stop long
before reaching I2C_NAME_SIZE.

Link: https://linux-hardware.org/?computer=AC4301C0542A
Fixes: bbb97d7 ("platform/x86: touchscreen_dmi: Add info for the Chuwi Hi8 Air tablet")
Closes: onitake/gsl-firmware#91
Cc: stable@vger.kernel.org
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240212120608.30469-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/platform/x86/touchscreen_dmi.c

@@ -81,7 +81,7 @@ static const struct property_entry chuwi_hi8_air_props[] = {
 };
 
 static const struct ts_dmi_data chuwi_hi8_air_data = {
-	.acpi_name	= "MSSL1680:00",
+	.acpi_name	= "MSSL1680",
 	.properties	= chuwi_hi8_air_props,
 };
 
@@ -1821,7 +1821,7 @@ static void ts_dmi_add_props(struct i2c_client *client)
 	int error;
 
 	if (has_acpi_companion(dev) &&
-	    !strncmp(ts_data->acpi_name, client->name, I2C_NAME_SIZE)) {
+	    strstarts(client->name, ts_data->acpi_name)) {
 		error = device_create_managed_software_node(dev, ts_data->properties, NULL);
 		if (error)
 			dev_err(dev, "failed to add properties: %d\n", error);