[PATCH 2/5] platform/x86: hp-wmi: handle firmware errors in tablet mode query

[Emre Cecanpunar <emreleno@gmail.com>]

hp_wmi_get_tablet_mode() accepts any nonnegative return value from
hp_wmi_perform_query() as success. HP firmware errors are positive, so a
rejected query makes the zeroed response look like laptop mode.

Treat every nonzero result as an error and preserve negative transport
errors. The event and resume paths pass the result directly to the input
subsystem, where a negative errno would look like an asserted switch, so
skip the switch update when the query fails.

Fixes: 520ee4ea1cc6 ("platform/x86: hp-wmi: Fix SW_TABLET_MODE detection method")
Signed-off-by: Emre Cecanpunar <emreleno@gmail.com>
---
 drivers/platform/x86/hp/hp-wmi.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
index 205a6020e9c5..e226b772ef00 100644
--- a/drivers/platform/x86/hp/hp-wmi.c
+++ b/drivers/platform/x86/hp/hp-wmi.c
@@ -798,8 +798,8 @@ static int hp_wmi_get_tablet_mode(void)
 	ret = hp_wmi_perform_query(HPWMI_SYSTEM_DEVICE_MODE, HPWMI_READ,
 				   system_device_mode, zero_if_sup(system_device_mode),
 				   sizeof(system_device_mode));
-	if (ret < 0)
-		return ret;
+	if (ret)
+		return ret < 0 ? ret : -EINVAL;
 
 	return system_device_mode[0] == DEVICE_MODE_TABLET;
 }
@@ -1198,7 +1198,7 @@ static void hp_wmi_notify(union acpi_object *obj, void *context)
 {
 	u32 event_id, event_data;
 	u32 *location;
-	int key_code;
+	int key_code, state;
 
 	if (!obj)
 		return;
@@ -1228,9 +1228,12 @@ static void hp_wmi_notify(union acpi_object *obj, void *context)
 		if (test_bit(SW_DOCK, hp_wmi_input_dev->swbit))
 			input_report_switch(hp_wmi_input_dev, SW_DOCK,
 					    hp_wmi_get_dock_state());
-		if (test_bit(SW_TABLET_MODE, hp_wmi_input_dev->swbit))
-			input_report_switch(hp_wmi_input_dev, SW_TABLET_MODE,
-					    hp_wmi_get_tablet_mode());
+		if (test_bit(SW_TABLET_MODE, hp_wmi_input_dev->swbit)) {
+			state = hp_wmi_get_tablet_mode();
+			if (state >= 0)
+				input_report_switch(hp_wmi_input_dev,
+						    SW_TABLET_MODE, state);
+		}
 		input_sync(hp_wmi_input_dev);
 		break;
 	case HPWMI_PARK_HDD:
@@ -2431,6 +2434,8 @@ static void __exit hp_wmi_bios_remove(struct platform_device *device)
 
 static int hp_wmi_resume_handler(struct device *device)
 {
+	int state;
+
 	/*
 	 * Hardware state may have changed while suspended, so trigger
 	 * input events for the current state. As this is a switch,
@@ -2441,9 +2446,12 @@ static int hp_wmi_resume_handler(struct device *device)
 		if (test_bit(SW_DOCK, hp_wmi_input_dev->swbit))
 			input_report_switch(hp_wmi_input_dev, SW_DOCK,
 					    hp_wmi_get_dock_state());
-		if (test_bit(SW_TABLET_MODE, hp_wmi_input_dev->swbit))
-			input_report_switch(hp_wmi_input_dev, SW_TABLET_MODE,
-					    hp_wmi_get_tablet_mode());
+		if (test_bit(SW_TABLET_MODE, hp_wmi_input_dev->swbit)) {
+			state = hp_wmi_get_tablet_mode();
+			if (state >= 0)
+				input_report_switch(hp_wmi_input_dev,
+						    SW_TABLET_MODE, state);
+		}
 		input_sync(hp_wmi_input_dev);
 	}