Re: [PATCH v3] of: property: add i2c-parent to fw_devlink supplier bindings

[Roman Gushchin <roman.gushchin@linux.dev>]

Rob Herring <robh@kernel.org> writes:

> On Sun, Aug 16, 2026 at 10:17:08PM -0700, Saravana Kannan wrote:
>> On Sat, Aug 15, 2026 at 8:33 PM Abdurrahman Hussain
>> <abdurrahman@nexthop.ai> wrote:
>> >
>> > Platform-device i2c muxes (i2c-mux-reg, i2c-mux-gpio, ...) reference
>> > the bus they multiplex with an i2c-parent phandle and hold a reference
>> > on that adapter from probe until remove. Unlike muxes that are clients
>> > on the parent bus, they live outside the adapter's device hierarchy,
>> > so nothing orders their teardown against it: if the adapter's device
>> > is unbound first — e.g. while reverting a device-tree overlay whose
>> > changeset attached the mux nodes before the controller nodes —
>> > i2c_del_adapter() blocks forever in
>> > wait_for_completion(&adap->dev_released), waiting for a reference that
>> > is only dropped later in the same teardown sequence.
>> >
>> > Teach fw_devlink about i2c-parent so the core creates the
>> > corresponding device links: consumers are unbound before the parent
>> > adapter's device, and probe ordering no longer needs -EPROBE_DEFER.
>> >
>> > A plain DEFINE_SIMPLE_PROP() cannot be used because the property has
>> > two incompatible layouts: the i2c mux bindings hold a list of bare
>> > phandles (i2c-demux-pinctrl takes several), while toshiba,tc9563 holds
>> > a single phandle followed by an i2c slave-address cell. The two forms
>> > are indistinguishable in the flattened tree, and a 0-cell parse of the
>> > tc9563 form would read the slave address as a phandle, linking the
>> > consumer to whatever node happens to carry that phandle value. Use a
>> > custom parser that only takes entry 0 for toshiba,tc9563 nodes.
>> >
>> > Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
>> > ---
>> > Changes in v3:
>> > - Fix the tc9563 compatible check: match "pci1179,0623" (the actual
>> >   binding compatible) instead of "toshiba,tc9563", which never matched
>> >   and let the bare-phandle parser misread the i2c slave-address cell as
>> >   a phandle (Sashiko AI review)
>> > - Link to v2: https://patch.msgid.link/20260815-b4-of-property-add-i2c-parent-v2-1-239c6da9e097@nexthop.ai
>> >
>> > Changes in v2:
>> > - Use a custom parser instead of DEFINE_SIMPLE_PROP: toshiba,tc9563 puts
>> >   an i2c slave-address cell after the phandle, which a 0-cell parse
>> >   would misread as a phandle (Sashiko AI review, Rob). Kept the full
>> 
>> A bit of a tangent, is this a bug in Sashiko bot?
>> It just dropped me from the reply in the v1 patch set. Any idea why?

Hm, can you, please, clarify, what do you mean?
https://sashiko.dev/#/patchset/20260813-b4-of-property-add-i2c-parent-v1-1-a2487e920ce1%40nexthop.ai
has your email in to according to the email policy.

Thanks!