Re: [PATCH] mfd: axp20x: preserve other control bits when powering off

[Chen-Yu Tsai]

On Fri, Jun 12, 2026 at 12:46 AM Oleg Proshkin <oleg.pro171@xxxxxxxxx> wrote:
>
> axp20x_power_off() triggers shutdown by writing AXP20X_OFF (BIT(7)) to
> the power-off control register with regmap_write(), which rewrites the
> whole register and clears other control bits in it.
>
> On the AXP221/AXP223 (and the register-compatible AXP228) - that
> register also holds the CHGLED auto-control bit.
> Clearing it during an orderly shutdown disables the hardware charge
> indicator, so the charge LED stays dark while the board is powered off
> and charging. Other variants keep unrelated configuration in the same
> register too.
>
> Set only the power-off bit with regmap_set_bits() and leave the rest of
> the register untouched. The shutdown register is readable on every
> variant, so the read-modify-write should be safe.
>
> Tested on a ClockworkPi uConsole (Raspberry Pi Compute Module 4, AXP228,
> which enumerates as AXP221): register AXP20X_OFF_CTRL reads 0x08 at
> runtime, so the old code left it 0x80 whereas setting only BIT(7)
> leaves 0x88. Writing 0x88 at power-off enables the charge LED
> while still powering off the PMIC.
>
> Signed-off-by: Oleg Proshkin <oleg.pro171@xxxxxxxxx>

Makes sense.

Reviewed-by: Chen-Yu Tsai <wens@xxxxxxxxxx>

> ---
>  drivers/mfd/axp20x.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
> index 679364189..50df66de2 100644
> --- a/drivers/mfd/axp20x.c
> +++ b/drivers/mfd/axp20x.c
> @@ -1253,7 +1253,7 @@ static int axp20x_power_off(struct sys_off_data *data)
>                 break;
>         }
>
> -       regmap_write(axp20x->regmap, shutdown_reg, AXP20X_OFF);
> +       regmap_set_bits(axp20x->regmap, shutdown_reg, AXP20X_OFF);
>
>         /* Give capacitors etc. time to drain to avoid kernel panic msg. */
>         mdelay(500);
> --
> 2.50.1 (Apple Git-155)
>