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

[Chen-Yu Tsai]

On Sun, Jun 5, 2016 at 9:50 PM, Hans de Goede <hdegoede at redhat.com> wrote:
> The kernel expects the power_off function to not return, and if it does
> it panics. At a slight delay after the i2c write which turns off power

             ^^^ Add?

Otherwise,

Acked-by: Chen-Yu Tsai <wens at csie.org>

> 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 at redhat.com>
> ---
>  drivers/mfd/axp20x.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
> index 6364dab..fd80b09 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>
> @@ -677,6 +678,9 @@ 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)
> --
> 2.7.4
>