Re: [PATCH v4 11/18] device property: Add remote endpoint to devcon matcher

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Sat, Aug 31, 2024 at 09:06:49PM -0700, Stephen Boyd wrote:
> When a single DT node has a graph connected to more than one
> usb-c-connector node we can't differentiate which typec switch
> registered for the device is associated with the USB connector because
> the devcon matcher code assumes a 1:1 relationship between remote node
> and typec switch. Furthermore, we don't have a #typec-switch-cells
> property so there can only be one node per typec switch.
> 
> Support multiple USB typec switches exposed by one node by passing the
> remote endpoint node in addition to the remote node to the devcon
> matcher function (devcon_match_fn_t). With this change, typec switch
> drivers can register switches with the device node pointer for a graph
> endpoint so that they can support more than one typec switch if
> necessary. Either way, a DT property like 'mode-switch' is always in the
> graph's parent node and not in the endpoint node.

> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Daniel Scally <djrscally@gmail.com>
> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Vinod Koul <vkoul@kernel.org>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Cc: Ivan Orlov <ivan.orlov0322@gmail.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> Cc: Conor Dooley <conor+dt@kernel.org>
> Cc: <devicetree@vger.kernel.org>
> Cc: <linux-usb@vger.kernel.org>
> Cc: <linux-acpi@vger.kernel.org>
> Cc: Pin-yen Lin <treapking@chromium.org>

Is it possible to move these Cc:s after --- line below?

> Signed-off-by: Stephen Boyd <swboyd@chromium.org>

...

>  /**
>   * devcon_match_fn_t - device connection match function
>   * @fwnode: Remote connection's device node
> + * @endpoint: Remote connection's endpoint node
>   * @con_id: Identifier for the connection
>   * @data: Match function caller specific data
>   *
>   * Implement a callback with this function signature to search a fwnode's
>   * connections for a match with a function like device_connection_find_match().
>   * This function will be called possibly multiple times, once for each
> - * connection. The match function should inspect the @fwnode to look for a
> - * match. The @con_id and @data provided are the same as the @con_id and @data
> - * arguments passed to the functions that take a devcon_match_fn_t argument.
> + * connection. The match function should inspect the connection's @fwnode
> + * and/or @endpoint to look for a match. The @con_id and @data provided are the
> + * same as the @con_id and @data arguments passed to the functions that take a
> + * devcon_match_fn_t argument.

So, struct fwnode_handle is a single-linked list. Can we utilise that instead
of adding a new parameter? I.o.w. do those objects (@fwnode and @endpoint) have
anything in common and can be chained?

>   * Note: This function can be called multiple times.

What does this mean? Is it idempotent? Or what is the effect of being called
multiple times?

>   *
>   * Return: Pointer to match or NULL if no match found.
>   */

-- 
With Best Regards,
Andy Shevchenko