From: Hans de Goede <hdegoede@redhat.com>
Date: Sun, 5 Jun 2016 13:50:48 +0000 (+0200)
Subject: mfd: axp20x: Add a 500ms delay at the end of axp20x_power_off
X-Git-Tag: v4.8-rc1~78^2~32
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=179dc63d06c51a78483dedbdf34540af053a6269;p=karo-tx-linux.git

mfd: axp20x: Add a 500ms delay at the end of axp20x_power_off

The kernel expects the power_off function to not return, and if it does
it panics. Add a slight delay after the i2c write which turns off power
through the PMIC, to give capacitors etc. some time to drain.

Without this the kernel lives on long enough after the poweroff to
print the following on the serial console on my Mele A1000G quad:

[  248.583588] reboot: Power down
[  248.600490] Kernel pa

With the delay the start of printing "Kernel panic" is gone.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---

diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
index ca04361a0ecd..a1ed43ea95aa 100644
--- a/drivers/mfd/axp20x.c
+++ b/drivers/mfd/axp20x.c
@@ -17,6 +17,7 @@
  */
 
 #include <linux/err.h>
+#include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -667,6 +668,9 @@ static void axp20x_power_off(void)
 
 	regmap_write(axp20x_pm_power_off->regmap, AXP20X_OFF_CTRL,
 		     AXP20X_OFF);
+
+	/* Give capacitors etc. time to drain to avoid kernel panic msg. */
+	msleep(500);
 }
 
 int axp20x_match_device(struct axp20x_dev *axp20x)