Re: [PATCH v3 0/8] of: property: Make fw_devlink follow GPIO, PWM and clock nexus maps

[Bartosz Golaszewski]

On Tue, 20 Oct 2026 15:00:11 +0200, Ernest Van Hoecke
<ernestvanhoecke@xxxxxxxxx> said:
> This series fixes an fw_devlink supplier-resolution problem reported by
> Leonardo Costa while using a Devicetree nexus to describe GPIO and PWM
> resources routed through an LVDS connector. Consumers referencing the
> nexus could remain deferred because fw_devlink linked them to the nexus
> rather than to the providers selected by gpio-map and pwm-map. [1]
>
> GPIO, PWM and clock consumer APIs use of_parse_phandle_with_args_map()
> to resolve specifiers through gpio-map, pwm-map and clock-map
> properties. The corresponding fw_devlink parsers use direct phandle
> parsing instead. Given a consumer which references a nexus, the consumer
> API and fw_devlink therefore resolve the reference to different nodes:
>
>   consumer API:  consumer -> nexus -> mapped provider
>   fw_devlink:    consumer -> nexus
>
> A nexus is a translation node rather than the resource provider and need
> not have a driver. The link to it can consequently remain unresolved and
> defer the consumer even though the mapped provider is available.
>
> Make the fw_devlink GPIO, PWM and clock parsers use the same map-aware
> resolver as their consumer APIs. The resolver also handles valid direct
> references by returning the original provider when no map is present.
> Use dedicated exact-name and suffix declaration macros to opt these
> bindings into map-aware parsing without changing unrelated property
> parsers. Retain GPIO's existing exclusions and compatibility handling.
>
> Since fw_devlink runs the resolver for every consumer when its device is
> created, patch 1 first fixes a stack buffer overflow in the resolver
> when the provider referenced by the consumer has more than
> MAX_PHANDLE_ARGS cells.
>
> The regression tests call the OF add_links operation and verify that a
> mapped reference creates exactly one link to the provider selected by
> the referenced map entry, not to the nexus. They also cover valid direct
> references. The GPIO tests exercise all property spellings recognized by
> fw_devlink, including the deprecated singular and unprefixed forms.
>
> The clock patch fixes aacc54c67869 ("clk: Add support for clock nexus dt
> bindings"), which has been in clk-next and linux-next with the same hash
> since next-20260907. There is no build-time dependency on it, but the
> clock patch should not reach mainline before it. The series applies to
> next-20261014.
>
> Tested with:
>   - The CONFIG_OF_UNITTEST cases under QEMU/x86_64: all passed. With the
>     fw_devlink parser changes reverted, exactly the six mapped consumer
>     cases fail.
>   - W=1 builds of each patch on arm64, including the OF unittest data
>   - Toradex Verdin iMX8M Plus hardware using a connector nexus for the
>     display GPIO and PWM resources (v2, same fw_devlink changes): the
>     display probes successfully
>
> [1] https://lore.kernel.org/all/juuc4af7ndbajcl7gzf4tg5qz2q2j5tt3rvql4jbauradujrre@gc5nbdhhixaf/
>
> Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@xxxxxxxxxxx>
>
> ---

Acked-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>