Re: [PATCH v6 03/16] power: sequencing: Add pwrseq_power_is_on()

On Tue, 21 Jul 2026 08:53:58 +0200, Chen-Yu Tsai <[email protected]> said:
> The power sequencing consumer API already does power on state tracking
> internally. Expose the state to consumers through pwrseq_power_is_on()
> so that they don't have to reimplement it locally.
>
> Acked-by: Bartosz Golaszewski <[email protected]>
> Signed-off-by: Chen-Yu Tsai <[email protected]>
> ---
> Changes since v5:
> - Reverted back to returning -EINVAL if descriptor is NULL
>
> Changes since v4:
> - Make pwrseq_power_is_on() return 1 if descriptor is NULL, i.e. if
>   the descriptor is optional, matching the other pwrseq consumer APIs
>
> Changes since v3:
> - Added missing stub function for !POWER_SEQUENCING
>
> Changes since v2:
> - New patch
>
> Needs to go in with "usb: hub: Power on connected M.2 E-key connectors"
> as it is a build time dependency. Bartosz wants the change on an
> immutable branch to pull into the pwrseq tree.
> ---
>  drivers/power/sequencing/core.c | 18 ++++++++++++++++++
>  include/linux/pwrseq/consumer.h |  6 ++++++
>  2 files changed, 24 insertions(+)
>
> diff --git a/drivers/power/sequencing/core.c b/drivers/power/sequencing/core.c
> index 02f42da91598..72b96d36920e 100644
> --- a/drivers/power/sequencing/core.c
> +++ b/drivers/power/sequencing/core.c
> @@ -968,6 +968,24 @@ int pwrseq_power_off(struct pwrseq_desc *desc)
>  }
>  EXPORT_SYMBOL_GPL(pwrseq_power_off);
>
> +/**
> + * pwrseq_power_is_on() - Queries the last requested state of the power sequencer.
> + * @desc: Descriptor referencing the power sequencer.
> + *
> + * This returns the last requested state of the power sequencer.
> + *
> + * Returns:
> + * On success, 1 for on and 0 for off; negative error number on failure.
> + */
> +int pwrseq_power_is_on(struct pwrseq_desc *desc)
> +{
> +	if (!desc)
> +		return -EINVAL;
> +
> +	return desc->powered_on;
> +}
> +EXPORT_SYMBOL_GPL(pwrseq_power_is_on);
> +

Didn't we agree on introducing an enum to make it future-proof for when we
also pull in pwrseq_is_controllable() from Loic?

I think this should work like so:

enum {
	PWRSEQ_STATE_UNKNOWN,
	PWRSEQ_STATE_ON,
	PWRSEQ_STATE_OFF,
};

int pwrseq_get_state(struct pwrseq_desc *desc)
{
	/* Only once this is upstream. */
	if (!pwrseq_is_controllable(desc))
		return PWRSEQ_STATE_UNKNOWN;

	return desc->powred_on ? PWRSEQ_STATE_ON : PWRSEQ_STATE_OFF;
}

Bart