platform/chrome: cros_ec_lightbar - Avoid I2C xfer to EC during suspend

A Mutex lock in cros_ec_cmd_xfer which may be held by frozen
Userspace thread during system suspending. So should not
call this routine in suspend thread.
Signed-off-by: Jeffery Yu <jefferyy@nvidia.com>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>

drivers/platform/chrome/cros_ec_dev.c

@@ -437,7 +437,6 @@ static int ec_device_probe(struct platform_device *pdev)
 		cros_ec_sensors_register(ec);
 
 	/* Take control of the lightbar from the EC. */
-	if (ec_has_lightbar(ec))
 	lb_manual_suspend_ctrl(ec, 1);
 
 	return 0;
@@ -452,7 +451,6 @@ static int ec_device_remove(struct platform_device *pdev)
 	struct cros_ec_dev *ec = dev_get_drvdata(&pdev->dev);
 
 	/* Let the EC take over the lightbar again. */
-	if (ec_has_lightbar(ec))
 	lb_manual_suspend_ctrl(ec, 0);
 
 	cros_ec_debugfs_remove(ec);
@@ -472,7 +470,6 @@ static int ec_device_suspend(struct device *dev)
 {
 	struct cros_ec_dev *ec = dev_get_drvdata(dev);
 
-	if (ec_has_lightbar(ec))
 	lb_suspend(ec);
 
 	return 0;
@@ -482,7 +479,6 @@ static int ec_device_resume(struct device *dev)
 {
 	struct cros_ec_dev *ec = dev_get_drvdata(dev);
 
-	if (ec_has_lightbar(ec))
 	lb_resume(ec);
 
 	return 0;

drivers/platform/chrome/cros_ec_lightbar.c

@@ -43,6 +43,7 @@ static unsigned long lb_interval_jiffies = 50 * HZ / 1000;
  * If this is true, we won't do anything during suspend/resume.
  */
 static bool userspace_control;
+static struct cros_ec_dev *ec_with_lightbar;
 
 static ssize_t interval_msec_show(struct device *dev,
 				  struct device_attribute *attr, char *buf)
@@ -384,6 +385,9 @@ int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
 	struct cros_ec_command *msg;
 	int ret;
 
+	if (ec != ec_with_lightbar)
+		return 0;
+
 	msg = alloc_lightbar_cmd_msg(ec);
 	if (!msg)
 		return -ENOMEM;
@@ -413,7 +417,7 @@ int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
 
 int lb_suspend(struct cros_ec_dev *ec)
 {
-	if (userspace_control)
+	if (userspace_control || ec != ec_with_lightbar)
 		return 0;
 
 	return lb_send_empty_cmd(ec, LIGHTBAR_CMD_SUSPEND);
@@ -421,7 +425,7 @@ int lb_suspend(struct cros_ec_dev *ec)
 
 int lb_resume(struct cros_ec_dev *ec)
 {
-	if (userspace_control)
+	if (userspace_control || ec != ec_with_lightbar)
 		return 0;
 
 	return lb_send_empty_cmd(ec, LIGHTBAR_CMD_RESUME);
@@ -606,9 +610,10 @@ static umode_t cros_ec_lightbar_attrs_are_visible(struct kobject *kobj,
 		return 0;
 
 	/* Only instantiate this stuff if the EC has a lightbar */
-	if (ec_has_lightbar(ec))
+	if (ec_has_lightbar(ec)) {
+		ec_with_lightbar = ec;
 		return a->mode;
-
+	}
 	return 0;
 }