linux-kernel - Re: [PATCH 2/2] video:omapdrm: make omapdrm assume the tv-out cable is always connected

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Message-ID: <3973104.FPbEEICOqe@avalon>
Date:	Fri, 13 Nov 2015 14:01:04 +0200
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Tomi Valkeinen <tomi.valkeinen@...com>
Cc:	"H. Nikolaus Schaller" <hns@...delico.com>,
	David Airlie <airlied@...ux.ie>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-fbdev@...r.kernel.org,
	gta04-owner@...delico.com, notasas@...il.com
Subject: Re: [PATCH 2/2] video:omapdrm: make omapdrm assume the tv-out cable is always connected

On Friday 13 November 2015 13:46:01 Tomi Valkeinen wrote:
> On 13/11/15 12:29, H. Nikolaus Schaller wrote:
> > Include VENC in the set of drivers where it is assimed that the cable
> > is always connected. Like DPI, DSI, DBI and SDI do.
> > 
> > Otherwise, the VENC will return cable status "unknown" and is not enabled
> > by the X-server. So there is no video output signal.
> > 
> > Tested on: BeagleBoard XM, GTA04 and OpenPandora
> > 
> > Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
> > ---
> > 
> >  drivers/gpu/drm/omapdrm/omap_connector.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/gpu/drm/omapdrm/omap_connector.c
> > b/drivers/gpu/drm/omapdrm/omap_connector.c index 83f2a91..98ddb5d 100644
> > --- a/drivers/gpu/drm/omapdrm/omap_connector.c
> > +++ b/drivers/gpu/drm/omapdrm/omap_connector.c
> > @@ -120,6 +120,7 @@ static enum drm_connector_status
> > omap_connector_detect(
> >  		else
> >  			ret = connector_status_disconnected;
> >  	} else if (dssdev->type == OMAP_DISPLAY_TYPE_DPI ||
> > +			dssdev->type == OMAP_DISPLAY_TYPE_VENC ||
> >  			dssdev->type == OMAP_DISPLAY_TYPE_DBI ||
> >  			dssdev->type == OMAP_DISPLAY_TYPE_SDI ||
> >  			dssdev->type == OMAP_DISPLAY_TYPE_DSI) {
> 
> I have no idea why VENC is not working for you when using
> connector_status_unknown, but I just tested DPI with
> connector_status_unknown (i.e. changed the above func to return unknown
> for DPI), and it works fine with X and X omap driver. And xrandr
> confirms that the connection status is unknown:
> 
> # xrandr
> Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 2048 x 2048
> HDMI-1 disconnected (normal left inverted right x axis y axis)
> None-1 unknown connection 1920x1200+0+0 (normal left inverted right x
> axis y axis) 0mm x 0mm
>    1920x1200     60.00*+  60.00 +
> 
> Grep also shows that there are many drivers using
> connector_status_unknown, so I'm guessing it should work fine...

And beside it's not right to consider VENC as always connected, as it isn't. 
The unknown status is there for a reason, to describe connectors for which we 
can't get any status information. The situation is different for DPI, DBI, SDI 
and DSI as those are on-board busses that connect to a non-removable panel, so 
we can say with a good confidence that the panel is connected (the situation 
could be changed with a hammer and a chisel, but that's unlikely to happen, 
hence the confidence).

-- 
Regards,

Laurent Pinchart

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