Re: [PATCH v5 2/7] drm/panel: simple: Add ability to override typical timing

From: Sam Ravnborg <sam@ravnborg.org>
To: Doug Anderson <dianders@chromium.org>
Cc: "Thierry Reding" <thierry.reding@gmail.com>,
	"Heiko Stuebner" <heiko@sntech.de>,
	"Sean Paul" <seanpaul@chromium.org>,
	devicetree@vger.kernel.org, "Rob Herring" <robh+dt@kernel.org>,
	"David Airlie" <airlied@linux.ie>,
	"Jeffy Chen" <jeffy.chen@rock-chips.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	"Boris Brezillon" <boris.brezillon@collabora.com>,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Enric Balletbò" <enric.balletbo@collabora.com>,
	"Stéphane Marchesin" <marcheu@chromium.org>,
	"Ezequiel Garcia" <ezequiel@collabora.com>,
	"Matthias Kaehlcke" <mka@chromium.org>
Subject: Re: [PATCH v5 2/7] drm/panel: simple: Add ability to override typical timing
Date: Thu, 11 Jul 2019 21:38:55 +0200	[thread overview]
Message-ID: <20190711193855.GB5912@ravnborg.org> (raw)
In-Reply-To: <CAD=FV=XnDTKkscdCwFE1137aX6pTtv=5zqXf=yqcnchpZpt5_Q@mail.gmail.com>

Hi Doug.

> > > > > @@ -91,6 +92,8 @@ struct panel_simple {
> > > > >       struct i2c_adapter *ddc;
> > > > >
> > > > >       struct gpio_desc *enable_gpio;
> > > > > +
> > > > > +     struct drm_display_mode override_mode;
> > > > I fail to see where this poiter is assigned.
> > >
> > > In panel_simple_parse_override_mode().  Specifically:
> > >
> > > drm_display_mode_from_videomode(&vm, &panel->override_mode);
> >
> > The above code-snippet is only called in the panel has specified display
> > timings using display_timings - it is not called when display_mode is
> > used.
> > So override_mode is only assigned in some cases and not all cases.
> > This needs to be fixed so we do not reference override_mode unless
> > it is set.
> 
> I'm afraid I'm not following you here.

> 
> * override_mode is a structure that's directly part of "struct panel_simple".
I had somehow confused myself to think this was a pointer.
And you are right that override_mode is properly initialized when the
structure is allocated.

Sorry for not reading the code and your replies carefully enough.

	Sam