Re: [PATCH V4 10/14] i3c: master: Add helper to query bus wakeup requirements

On Thu, Aug 06, 2026 at 04:18:53PM +0300, Adrian Hunter wrote:
> Add i3c_master_has_wakeup_enabled_devs(), 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 <[email protected]>
> ---

Reviewed-by: Frank Li <[email protected]>

>
>
> Changes in V4:
>
> 	Renamed i3c_master_any_wakeup_enabled() to
> 	i3c_master_has_wakeup_enabled_devs().
>
> Changes in V3:
>
> 	Skip the master device explicitly.  Added kernel-doc noting
> 	that wakeup enablement is user space policy, so the helper is
> 	meant to be called from a system suspend callback.
>
> 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       | 35 +++++++++++++++++++++++++++++++++++
>  include/linux/i3c/master.h |  1 +
>  2 files changed, 36 insertions(+)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index 6c5341491944..afcd7a21a3e6 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -2147,6 +2147,41 @@ static void i3c_master_reg_work_fn(struct work_struct *work)
>  	i3c_master_register_new_i3c_devs(master);
>  }
>
> +/**
> + * i3c_master_has_wakeup_enabled_devs() - 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.
> + *
> + * Whether a device is enabled for system wakeup is user space policy,
> + * settable at any time through the device's power/wakeup sysfs attribute,
> + * so the answer is only stable once user space is frozen.  Call this from
> + * a system suspend callback.
> + *
> + * Return: true if any device may wake the system via IBI, false otherwise.
> + */
> +bool i3c_master_has_wakeup_enabled_devs(struct i3c_master_controller *master)
> +{
> +	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 || desc == master->this || !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_has_wakeup_enabled_devs);
> +
>  /**
>   * 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 9d675d01522c..82d9886e7f12 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -765,6 +765,7 @@ 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_has_wakeup_enabled_devs(struct i3c_master_controller *master);
>
>  struct i3c_ibi_slot *i3c_master_get_free_ibi_slot(struct i3c_dev_desc *dev);
>
> --
> 2.53.0
>

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