platform/x86: intel-vbtn: Only blacklist SW_TABLET_MODE on the 9 / "Laptop" chasis-type

The HP Stream x360 11-p000nd no longer report SW_TABLET_MODE state / events
with recent kernels. This model reports a chassis-type of 10 / "Notebook"
which is not on the recently introduced chassis-type whitelist

Commit de9647ef ("platform/x86: intel-vbtn: Only activate tablet mode
switch on 2-in-1's") added a chassis-type whitelist and only listed 31 /
"Convertible" as being capable of generating valid SW_TABLET_MOD events.

Commit 1fac39fd ("platform/x86: intel-vbtn: Also handle tablet-mode
switch on "Detachable" and "Portable" chassis-types") extended the
whitelist with chassis-types 8 / "Portable" and 32 / "Detachable".

And now we need to exten the whitelist again with 10 / "Notebook"...

The issue original fixed by the whitelist is really a ACPI DSDT bug on
the Dell XPS 9360 where it has a VGBS which reports it is in tablet mode
even though it is not a 2-in-1 at all, but a regular laptop.

So since this is a workaround for a DSDT issue on that specific model,
instead of extending the whitelist over and over again, lets switch to
a blacklist and only blacklist the chassis-type of the model for which
the chassis-type check was added.

Note this also fixes the current version of the code no longer checking
if dmi_get_system_info(DMI_CHASSIS_TYPE) returns NULL.

Fixes: 1fac39fd ("platform/x86: intel-vbtn: Also handle tablet-mode switch on "Detachable" and "Portable" chassis-types")
Cc: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mario Limonciello <Mario.limonciello@dell.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/intel-vbtn.c

@@ -170,21 +170,18 @@ static bool intel_vbtn_has_buttons(acpi_handle handle)
 static bool intel_vbtn_has_switches(acpi_handle handle)
 {
 	const char *chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
-	unsigned long chassis_type_int;
 	unsigned long long vgbs;
 	acpi_status status;
 
-	if (kstrtoul(chassis_type, 10, &chassis_type_int))
-		return false;
-
-	switch (chassis_type_int) {
-	case  8: /* Portable */
-	case 31: /* Convertible */
-	case 32: /* Detachable */
-		break;
-	default:
+	/*
+	 * Some normal laptops have a VGBS method despite being non-convertible
+	 * and their VGBS method always returns 0, causing detect_tablet_mode()
+	 * to report SW_TABLET_MODE=1 to userspace, which causes issues.
+	 * These laptops have a DMI chassis_type of 9 ("Laptop"), do not report
+	 * switches on any devices with a DMI chassis_type of 9.
+	 */
+	if (chassis_type && strcmp(chassis_type, "9") == 0)
 		return false;
-	}
 
 	status = acpi_evaluate_integer(handle, "VGBS", NULL, &vgbs);
 	return ACPI_SUCCESS(status);