Re: [PATCH v1 01/16] drm/bridge: tc358767: fix opencoded use of drm_panel_*

From: Sam Ravnborg <sam@ravnborg.org>
To: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Neil Armstrong <narmstrong@baylibre.com>,
	David Airlie <airlied@linux.ie>,
	dri-devel@lists.freedesktop.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Marek Vasut <marex@denx.de>,
	linux-samsung-soc@vger.kernel.org, Sean Paul <sean@poorly.run>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Kukjin Kim <kgene@kernel.org>, NXP Linux Team <linux-imx@nxp.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Alison Wang <alison.wang@nxp.com>,
	Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>,
	Alexios Zavras <alexios.zavras@intel.com>,
	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
	linux-tegra@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Vincent Abriou <vincent.abriou@st.com>,
	Allison Randal <allison@lohutok.net>,
	linux-arm-kernel@lists.infradead.org,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Enrico Weigelt <info@metux.net>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Shawn Guo <shawnguo@kernel.org>
Subject: Re: [PATCH v1 01/16] drm/bridge: tc358767: fix opencoded use of drm_panel_*
Date: Mon, 5 Aug 2019 13:53:00 +0200	[thread overview]
Message-ID: <20190805115300.GA16513@ravnborg.org> (raw)
In-Reply-To: <1564997756.3056.13.camel@pengutronix.de>

Hi Philipp.

On Mon, Aug 05, 2019 at 11:35:56AM +0200, Philipp Zabel wrote:
> On Sun, 2019-08-04 at 22:16 +0200, Sam Ravnborg wrote:
> > Replace open coded version with call to drm_panel_get_modes().
> > 
> > Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> > Cc: Andrzej Hajda <a.hajda@samsung.com>
> > Cc: Neil Armstrong <narmstrong@baylibre.com>
> > Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
> > Cc: Jonas Karlman <jonas@kwiboo.se>
> > Cc: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> >  drivers/gpu/drm/bridge/tc358767.c | 10 ++++------
> >  1 file changed, 4 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
> > index 42f03a985ac0..cebc8e620820 100644
> > --- a/drivers/gpu/drm/bridge/tc358767.c
> > +++ b/drivers/gpu/drm/bridge/tc358767.c
> > @@ -1312,7 +1312,7 @@ static int tc_connector_get_modes(struct drm_connector *connector)
> >  {
> >  	struct tc_data *tc = connector_to_tc(connector);
> >  	struct edid *edid;
> > -	unsigned int count;
> > +	int count;
> 
> This looks like it also fixes a potential bug ...

get_modes() return either 0 or number of modes.
The negative return values come into play in drm_panel_get_modes() when
panel for example s NULL.

I will add this to changelog before I apply to avoid any
misunderstanding.

	Sam

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