linux-kernel - Re: [PATCH v2] drm/bridge: Fix assignment of the of

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Message-ID: <ZyOsuTr4XBU3ogRx@linaro.org>
Date: Thu, 31 Oct 2024 18:13:45 +0200
From: Abel Vesa <abel.vesa@...aro.org>
To: Johan Hovold <johan@...nel.org>
Cc: 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>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v2] drm/bridge: Fix assignment of the of_node of the
 parent to aux bridge

On 24-10-31 15:05:52, Johan Hovold wrote:
> On Mon, Oct 21, 2024 at 09:23:24AM +0200, Johan Hovold wrote:
> > On Fri, Oct 18, 2024 at 03:49:34PM +0300, Abel Vesa wrote:
> > > The assignment of the of_node to the aux bridge needs to mark the
> > > of_node as reused as well, otherwise resource providers like pinctrl will
> > > report a gpio as already requested by a different device when both pinconf
> > > and gpios property are present.
> > 
> > I don't think you need a gpio property for that to happen, right? And
> > this causes probe to fail IIRC?

Yes, I think this is actually because of the pinctrl property in the node,
so no gpio needed.

Yes, probe fails.

> > 
> > > Fix that by using the device_set_of_node_from_dev() helper instead.
> > > 
> > > Fixes: 6914968a0b52 ("drm/bridge: properly refcount DT nodes in aux bridge drivers")
> > 
> > This is not the commit that introduced the issue.

The proper fixes tag here is actually:

Fixes: 2a04739139b2 ("drm/bridge: add transparent bridge helper")

> > 
> > > Cc: stable@...r.kernel.org      # 6.8

> > 
> > I assume there are no existing devicetrees that need this since then we
> > would have heard about it sooner. Do we still need to backport it?

None of the DTs I managed to scan seem to have this problem.

Maybe backporting it is not worth it then.

> > 
> > When exactly are you hitting this?

Here is one of the examples.

[    5.768283] x1e80100-tlmm f100000.pinctrl: error -EINVAL: pin-185 (aux_bridge.aux_bridge.3)
[    5.768289] x1e80100-tlmm f100000.pinctrl: error -EINVAL: could not request pin 185 (GPIO_185) from group gpio185 on device f100000.pinctrl
[    5.768293] aux_bridge.aux_bridge aux_bridge.aux_bridge.3: Error applying setting, reverse things back

> 
> Abel, even if Neil decided to give me the finger here, please answer the
> above so that it's recorded in the archives at least.
> 
> Johan
> 

Sorry for not replying in time before the patch was merge.

Abel.