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 ca04361a0ecd186065e8b5834ddf4c14313094c5..a1ed43ea95aa15f990c180187b01a372b0049739 100644 (file)
--- 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)