linux-kernel - Re: [PATCH v4 20/25] drm/tilcdc: Use devm_drm_of_get

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Message-ID: <20260122160311.658cc219@kmaincent-XPS-13-7390>
Date: Thu, 22 Jan 2026 16:03:11 +0100
From: Kory Maincent <kory.maincent@...tlin.com>
To: Maxime Ripard <mripard@...nel.org>
Cc: Luca Ceresoli <luca.ceresoli@...tlin.com>, Jyri Sarha
 <jyri.sarha@....fi>, Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann
 <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter
 <simona@...ll.ch>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Russell King
 <linux@...linux.org.uk>, Bartosz Golaszewski <brgl@...ev.pl>, Tony Lindgren
 <tony@...mide.com>, Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong
 <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, Laurent
 Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman
 <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, Markus
 Schneider-Pargmann <msp@...libre.com>, Bajjuri Praneeth <praneeth@...com>,
 Louis Chauvet <louis.chauvet@...tlin.com>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>, Miguel Gazquez
 <miguel.gazquez@...tlin.com>, Herve Codina <herve.codina@...tlin.com>,
 dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-omap@...r.kernel.org
Subject: Re: [PATCH v4 20/25] drm/tilcdc: Use devm_drm_of_get_bridge()
 helper

On Thu, 22 Jan 2026 15:03:21 +0100
Maxime Ripard <mripard@...nel.org> wrote:

> Hi,
> 
> On Mon, Jan 19, 2026 at 10:18:12PM +0100, Luca Ceresoli wrote:
> > Maxime, I'd appreciate your opinion about the topic below.
> > 
> > > -	int ret;
> > >
> > > -	ret = drm_of_find_panel_or_bridge(ddev->dev->of_node, 0, 0,
> > > -					  &panel, &bridge);
> > > -	if (ret == -ENODEV)
> > > +	bridge = devm_drm_of_get_bridge(ddev->dev, ddev->dev->of_node,
> > > 0, 0);
> > > +	if (PTR_ERR(bridge) == -ENODEV)  
> > 
> > This patch is technically OK in the sense that the code before and after
> > would be equivalent. However if it were me I would not do this change. The
> > reason is that both drm_of_find_panel_or_bridge() and *_of_get_bridge() are
> > problematic when introducing drm_bridge hotplug, which is the long-term
> > goal I am working for, but *_of_get_bridge() is more problematic than
> > drm_of_find_panel_or_bridge().
> > 
> > These functions are still there and not deprecated because there is
> > currently no better replacement (and drm_bridge hotplug is not yet
> > supported because of this and other things still to be done). To have a
> > replacement, the panel_bridge lifetime needs to be reworked first and
> > that's not going to happen overnight. So, all in all, if this patch is not
> > crucial to your series I'd consider dropping it. But if it is important I'm
> > fine with applying it, it won't make a huge difference.  
> 
> Eh. I'm fine either way. I understand what you're saying, but this patch
> doesn't introduce any *new* problem while it cleans up the driver, so I
> guess we could merge it still. And further clean it up with what you
> were suggesting later on.

As you want. I will then keep the patch. If anyone has reasons why these
patch should not be merged, speak now or forever hold your peace! ^^

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com