[PATCH] ACPI/Battery: Retry to get Battery information if failed during probing

[Lan Tianyu <tianyu.lan@intel.com>]

Some machines'(E,G Lenovo Z480) ECs are not stable during boot up
and causes battery driver fails to be probed due to failure of getting
battery information from EC sometimes. After several retries, the
operation will work. This patch is to retry to get battery information 5
times if the first try fails.

Reported-and-tested-by: naszar <naszar@ya.ru>
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=75581
Cc: stable@vger.kernel.org
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
---
 drivers/acpi/battery.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index e48fc98..485009d 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -34,6 +34,7 @@
 #include <linux/dmi.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
+#include <linux/delay.h>
 #include <asm/unaligned.h>
 
 #ifdef CONFIG_ACPI_PROCFS_POWER
@@ -1119,7 +1120,7 @@ static struct dmi_system_id bat_dmi_table[] = {
 
 static int acpi_battery_add(struct acpi_device *device)
 {
-	int result = 0;
+	int result = 0, retry = 5;
 	struct acpi_battery *battery = NULL;
 
 	if (!device)
@@ -1135,7 +1136,16 @@ static int acpi_battery_add(struct acpi_device *device)
 	mutex_init(&battery->sysfs_lock);
 	if (acpi_has_method(battery->device->handle, "_BIX"))
 		set_bit(ACPI_BATTERY_XINFO_PRESENT, &battery->flags);
+
+retry_get_info:
 	result = acpi_battery_update(battery, false);
+
+	if (result && retry) {
+		msleep(20);
+		retry--;
+		goto retry_get_info;
+	}
+
 	if (result)
 		goto fail;
 #ifdef CONFIG_ACPI_PROCFS_POWER
-- 
1.8.4.rc0.1.g8f6a3e5.dirty