Re: [PATCH V2 4/8] i3c: master: Add helper to query bus wakeup requirements

[Frank Li]

On Tue, Jul 28, 2026 at 06:53:04PM +0300, Adrian Hunter wrote:
> Add i3c_master_any_wakeup_enabled(), which iterates over the devices on
> an I3C bus and reports whether any of them are enabled for system
> wakeup and have IBI enabled.
>
> Controller drivers can use this helper to determine whether wakeup
> support must remain available while the system is suspended.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
>
>
> Changes in V2:
>
> 	i3c_master_any_wakeup_enabled() now also requires the device to
> 	have IBI enabled, not just system wakeup enabled, so that a
> 	device with no active IBI request does not keep PCI PME enabled.
> 	desc->ibi_lock is taken while checking.  The commit message and
> 	kernel-doc are updated to match.
>
>
>  drivers/i3c/master.c       | 30 ++++++++++++++++++++++++++++++
>  include/linux/i3c/master.h |  1 +
>  2 files changed, 31 insertions(+)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 9d56ca08569a..dd49652425b4 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -2048,6 +2048,36 @@ static void i3c_master_reg_work_fn(struct work_struct *work)
>  	i3c_master_register_new_i3c_devs(master);
>  }
>
> +/**
> + * i3c_master_any_wakeup_enabled() - check if any device can wake the system
> + * @master: I3C master controller
> + *
> + * Iterate over devices on the bus and return true if any device has
> + * system wakeup enabled and IBI enabled.
> + *
> + * Return: true if any device may wake the system via IBI, false otherwise.
> + */
> +bool i3c_master_any_wakeup_enabled(struct i3c_master_controller *master)
> +{

This check most like introdouce rise condition.

if (i3c_master_any_wakeup_enabled())
	do_some_thing()

no lock protection, so between check i3c_master_any_wakeup_enabled() and
do_some_thing(), condtion may be changed.

Frank

> +	struct i3c_dev_desc *desc;
> +	bool wakeup = false;
> +
> +	i3c_bus_normaluse_lock(&master->bus);
> +	i3c_bus_for_each_i3cdev(&master->bus, desc) {
> +		if (!desc->dev || !device_may_wakeup(&desc->dev->dev))
> +			continue;
> +		guard(mutex)(&desc->ibi_lock);
> +		if (desc->ibi && desc->ibi->enabled) {
> +			wakeup = true;
> +			break;
> +		}
> +	}
> +	i3c_bus_normaluse_unlock(&master->bus);
> +
> +	return wakeup;
> +}
> +EXPORT_SYMBOL_GPL(i3c_master_any_wakeup_enabled);
> +
>  /**
>   * i3c_master_dma_map_single() - Map buffer for single DMA transfer
>   * @dev: device object of a device doing DMA
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index 99f89fef7653..d8cdc7ff2459 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -748,6 +748,7 @@ void i3c_generic_ibi_recycle_slot(struct i3c_generic_ibi_pool *pool,
>  				  struct i3c_ibi_slot *slot);
>
>  void i3c_master_queue_ibi(struct i3c_dev_desc *dev, struct i3c_ibi_slot *slot);
> +bool i3c_master_any_wakeup_enabled(struct i3c_master_controller *master);
>
>  struct i3c_ibi_slot *i3c_master_get_free_ibi_slot(struct i3c_dev_desc *dev);
>
> --
> 2.53.0
>