linux-kernel - Re: [PATCH] drm/bridge: ti-sn65dsi83: use dev_err

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Message-ID: <20240813101643.5bf8d245@booty>
Date: Tue, 13 Aug 2024 10:16:43 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Andi Shyti <andi.shyti@...ux.intel.com>
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>, Daniel Vetter <daniel@...ll.ch>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: ti-sn65dsi83: use dev_err_probe when
 failing to get panel bridge

Hello Andi,

On Thu, 8 Aug 2024 11:35:23 +0100
Andi Shyti <andi.shyti@...ux.intel.com> wrote:

> Hi Luca,
> 
> On Thu, Aug 08, 2024 at 12:26:14PM +0200, Luca Ceresoli wrote:
> > When devm_drm_of_get_bridge() fails, the probe fails silently. Use
> > dev_err_probe() instead to log an error or report the deferral reason,
> > whichever is applicable.
> > 
> > Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
> > ---
> >  drivers/gpu/drm/bridge/ti-sn65dsi83.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> > index 57a7ed13f996..60b9f14d769a 100644
> > --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> > @@ -606,7 +606,7 @@ static int sn65dsi83_parse_dt(struct sn65dsi83 *ctx, enum sn65dsi83_model model)
> >  
> >  	panel_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 2, 0);
> >  	if (IS_ERR(panel_bridge))
> > -		return PTR_ERR(panel_bridge);
> > +		return dev_err_probe(dev, PTR_ERR(panel_bridge), "Failed to get panel bridge\n");  
> 
> patch looks good, but the message is a bit misleading. You are
> not failing to get the panel bridge, but you are failing to find
> a panel bridge in a DT node. Right?

As I can see from both the documentation and the code,
devm_drm_of_get_bridge() is really returning a pointer to a panel
bridge, potentially allocating and adding it in case it was not present
before. Navigating the device tree is only a part of what it does.

Do you think I am missing something?

Luca

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com