greybus: gpio: add error messages to callbacks not propagating errors

Add error messages on failures to deactivate, set and get operation
handlers as any errors would not be detected by the upper layers (either
because the callbacks are declared void or expected to return a boolean
value).
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/gpio.c

@@ -184,8 +184,13 @@ static void gb_gpio_deactivate_operation(struct gb_gpio_controller *ggc,
 	request.which = which;
 	ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_DEACTIVATE,
 				 &request, sizeof(request), NULL, 0);
-	if (!ret)
-		ggc->lines[which].active = false;
+	if (ret) {
+		dev_err(ggc->chip.dev, "failed to deactivate gpio %u\n",
+			which);
+		return;
+	}
+
+	ggc->lines[which].active = false;
 }
 
 static int gb_gpio_get_direction_operation(struct gb_gpio_controller *ggc,
@@ -254,8 +259,11 @@ static int gb_gpio_get_value_operation(struct gb_gpio_controller *ggc,
 	ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_GET_VALUE,
 				&request, sizeof(request),
 				&response, sizeof(response));
-	if (ret)
+	if (ret) {
+		dev_err(ggc->chip.dev, "failed to get value of gpio %u\n",
+			which);
 		return ret;
+	}
 
 	value = response.value;
 	if (value && value != 1) {
@@ -283,8 +291,13 @@ static void gb_gpio_set_value_operation(struct gb_gpio_controller *ggc,
 	request.value = value_high ? 1 : 0;
 	ret = gb_operation_sync(ggc->connection, GB_GPIO_TYPE_SET_VALUE,
 				&request, sizeof(request), NULL, 0);
-	if (!ret)
-		ggc->lines[which].value = request.value;
+	if (ret) {
+		dev_err(ggc->chip.dev, "failed to set value of gpio %u\n",
+			which);
+		return;
+	}
+
+	ggc->lines[which].value = request.value;
 }
 
 static int gb_gpio_set_debounce_operation(struct gb_gpio_controller *ggc,