Re: [PATCH 6/8] i3c: master: Defer new-device registration out of DAA caller context

[Frank Li <Frank.li@nxp.com>]

On Tue, May 12, 2026 at 03:17:30PM +0300, Adrian Hunter wrote:
> Master drivers may invoke i3c_master_do_daa_ext() during resume to
> re-run Dynamic Address Assignment.  As well as assigning addresses to
> any newly arrived devices, this restores the dynamic address of devices
> that lost it across system suspend, so it has to run as part of the
> controller's resume path.
>
> A side effect of i3c_master_do_daa_ext() today is that it also
> registers any newly discovered I3C devices with the driver model
> inline, via i3c_master_register_new_i3c_devs().  Doing that from the
> resume path is problematic: a hot-join-capable device may join the bus
> during this same DAA, and registering it immediately would push driver
> model work (probing, sysfs, etc.) into the controller's resume context,
> where the rest of the system is not yet fully resumed and the
> controller driver is still partway through its own resume sequence.
>
> Decouple discovery from registration: add a reg_work work item to
> struct i3c_master_controller and have i3c_master_do_daa_ext() queue it
> on master->wq (the freezable workqueue) instead of calling
> i3c_master_register_new_i3c_devs() directly.  The worker performs the
> registration only when the controller is not shutting_down, and is
> cancelled alongside hj_work in i3c_master_shutdown().  Because wq is
> freezable, any newly observed devices end up being registered after
> the system has finished resuming.
>
> i3c_master_register() also routes its initial post-bus-init registration
> through reg_work, using flush_work() to keep probe-time behavior
> synchronous.  This keeps a single registration code path and ensures the
> worker is the only writer of desc->dev.

why not direct use hj_work?

Frank
>