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Date:   Thu, 24 Nov 2022 14:24:49 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Pin-yen Lin <treapking@chromium.org>
Cc:     Andrzej Hajda <andrzej.hajda@intel.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Robert Foss <robert.foss@linaro.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Daniel Scally <djrscally@gmail.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Prashant Malani <pmalani@chromium.org>,
        Benson Leung <bleung@chromium.org>,
        Guenter Roeck <groeck@chromium.org>,
        Javier Martinez Canillas <javierm@redhat.com>,
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        dri-devel@lists.freedesktop.org,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        devicetree@vger.kernel.org, chrome-platform@lists.linux.dev,
        linux-acpi@vger.kernel.org, Marek Vasut <marex@denx.de>,
        Xin Ji <xji@analogixsemi.com>, Lyude Paul <lyude@redhat.com>,
        =?iso-8859-1?Q?N=EDcolas_F_=2E_R_=2E_A_=2E?= Prado 
        <nfraprado@collabora.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        linux-kernel@vger.kernel.org, Allen Chen <allen.chen@ite.com.tw>
Subject: Re: [PATCH v6 2/7] platform/chrome: cros_ec_typec: Purge blocking
 switch devlinks
Message-ID: <Y39ikbcqx5/pEc64@smile.fi.intel.com>
References: <20221124102056.393220-1-treapking@chromium.org>
 <20221124102056.393220-3-treapking@chromium.org>
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On Thu, Nov 24, 2022 at 06:20:51PM +0800, Pin-yen Lin wrote:
> From: Prashant Malani <pmalani@chromium.org>
> 
> When using OF graph, the fw_devlink code will create links between the
> individual port driver (cros-ec-typec here) and the parent device for
> a Type-C switch (like mode-switch). Since the mode-switch will in turn
> have the usb-c-connector (i.e the child of the port driver) as a
> supplier, fw_devlink will not be able to resolve the cyclic dependency
> correctly.
> 
> As a result, the mode-switch driver probe() never runs, so mode-switches
> are never registered. Because of that, the port driver probe constantly
> fails with -EPROBE_DEFER, because the Type-C connector class requires all
> switch devices to be registered prior to port registration.
> 
> To break this deadlock and allow the mode-switch registration to occur,
> purge all the usb-c-connector nodes' absent suppliers. This eliminates
> the connector as a supplier for a switch and allows it to be probed.

...

> +	/*
> +	 * OF graph may have set up some device links with switches, since connectors have their
> +	 * own compatible. Purge these to avoid a deadlock in switch probe (the switch mistakenly
> +	 * assumes the connector is a supplier).
> +	 */

A bit too long lines...

> +	if (dev->of_node)

Why do you need this check?

> +		device_for_each_child_node(dev, fwnode)
> +			fw_devlink_purge_absent_suppliers(fwnode);

-- 
With Best Regards,
Andy Shevchenko