Re: [PATCH 1/4] driver: core: introduce dev_add_sync_state()

[Brian Masney <bmasney@redhat.com>]

On Mon, Jun 29, 2026 at 12:11:18PM +0200, Konrad Dybcio wrote:
> On 6/26/26 6:32 PM, Brian Masney wrote:
> > We have cases where a device node represents a provider for multiple
> > types of resources, like clocks, power-domains, resets, etc. We
> > currently have dev_set_drv_sync_state() where a framework or driver
> > can set the sync_state callback for a device node, however it currently
> > only supports a single sync_state callback.
> > 
> > The pmdomain subsystem currently sets up a sync_state callback in the
> > core framework, and the clk subsystem will setup it's own separate
> > sync_state callback in the core framework. These can collide with each
> > other on some types of devices that have multiple types of resources.
> > Additionally, some clk drivers already have their own separate
> > sync_state callback already defined.
> > 
> > Let's introduce support for allowing drivers and frameworks to add their
> > own sync_state callback via a new function dev_add_sync_state() so that
> > multiple sync_state callbacks can coexist.
> > 
> > Link: https://lore.kernel.org/linux-clk/CAPx+jO9JiV16ePLk59hTQzEMnA96Va6Ns4jqJbwyZ6oTT0AjXA@mail.gmail.com/
> > Signed-off-by: Brian Masney <bmasney@redhat.com>
> > Assisted-by: Claude:claude-opus-4-6
> > ---
> 
> [...]
> 
> > +int dev_add_sync_state(struct device *dev,
> > +			   void (*fn)(struct device *dev))
> > +{
> > +	struct sync_state_entry *entry;
> > +
> > +	if (!dev || !dev->driver)
> > +		return 0;
> > +
> > +	list_for_each_entry(entry, &dev->sync_state_list, node)
> > +		if (entry->fn == fn)
> > +			return 0;
> 
> Do we expect this to be a valid call, i.e. should we WARN_ON here?

That's a good point about adding a WARN_ON() here. I kept this logic
from when I converted from dev_set_drv_sync_state().

Brian