Re: [PATCH v13 05/10] drm/bridge: anx7625: Check for Type-C during panel registration - Pin-yen Lin

From: Pin-yen Lin <treapking@chromium.org>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Andrzej Hajda" <andrzej.hajda@intel.com>,
	"Neil Armstrong" <neil.armstrong@linaro.org>,
	"Robert Foss" <rfoss@kernel.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>,
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	"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>,
	"Xin Ji" <xji@analogixsemi.com>,
	"Javier Martinez Canillas" <javierm@redhat.com>,
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	linux-kernel@vger.kernel.org,
	"AngeloGioacchino Del Regno"
	<angelogioacchino.delregno@collabora.com>,
	chrome-platform@lists.linux.dev,
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	"Marek Vasut" <marex@denx.de>,
	"Hsin-Yi Wang" <hsinyi@chromium.org>,
	devicetree@vger.kernel.org, "Allen Chen" <allen.chen@ite.com.tw>,
	dri-devel@lists.freedesktop.org,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Stephen Boyd" <swboyd@chromium.org>,
	linux-acpi@vger.kernel.org,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Subject: Re: [PATCH v13 05/10] drm/bridge: anx7625: Check for Type-C during panel registration
Date: Wed, 8 Mar 2023 18:25:00 +0800	[thread overview]
Message-ID: <CAEXTbpecGhEDrffDobb4NgLw8+vMK2_yVmJw8JGUDruTALm4-w@mail.gmail.com> (raw)
In-Reply-To: <ZAXT0JFjERb8Q36f@smile.fi.intel.com>

HI Andy,

On Mon, Mar 6, 2023 at 7:52 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Fri, Mar 03, 2023 at 10:33:45PM +0800, Pin-yen Lin wrote:
> > The output port endpoints can be connected to USB-C connectors.
> > Running drm_of_find_panel_or_bridge() with such endpoints leads to
> > a continuous return value of -EPROBE_DEFER, even though there is
> > no panel present.
> >
> > To avoid this, check for the existence of a "mode-switch" property in
> > the port endpoint, and skip panel registration completely if so.
>
> ...
>
> > +     port_node = of_graph_get_port_by_id(np, 1);
> > +     count = typec_mode_switch_node_count(&port_node->fwnode);
>
> Do you need to drop reference count here?
> (I don't know myself, so, please check this)
>
> If no, patch LGTM.

The helper completes the for-loop of fwnode_for_each_child_node, which
drops the reference count whenever the next node is get. So we don't
need drop the reference count here.
>
> > +     if (count)
> > +             return 0;
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
Best regards,
Pin-yen