Here the test results:

Am 13.11.2015 um 13:01 schrieb Laurent Pinchart [off-list ref]:

On Friday 13 November 2015 13:46:01 Tomi Valkeinen wrote:

quoted

On 13/11/15 12:29, H. Nikolaus Schaller wrote:

quoted

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 <redacted>
---

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 +

A) with this VENC patch:

root@letux:~# xrandr
Screen 0: minimum 320 x 200, current 720 x 640, maximum 2048 x 2048
None-1 connected 720x574+0+0 0mm x 0mm
   720x574i      50.00*+
None-2 connected 480x640+0+0 0mm x 0mm
   480x640       65.74*+
root@letux:~# cat /sys/class/drm/card0-Unknown-*/enabled
enabled
enabled
root@letux:~# cat /sys/class/drm/card0-Unknown-*/status 
connected
connected

B) w/o VENC patch (VENC returns returning connector_status_unknown):

root@letux:~# xrandr
Screen 0: minimum 320 x 200, current 480 x 640, maximum 2048 x 2048
None-1 connected 480x640+0+0 0mm x 0mm
   480x640       65.74*+
None-2 unknown connection
   720x574i      50.00 +
root@letux:~# cat /sys/class/drm/card0-Unknown-*/enabled
enabled
disabled
root@letux:~# cat /sys/class/drm/card0-Unknown-*/status
connected
unknown

C) with DPI (also) returning connector_status_unknown

root@letux:~# xrandr
Screen 0: minimum 320 x 200, current 720 x 640, maximum 2048 x 2048
None-1 unknown connection 720x574+0+0 0mm x 0mm
   720x574i      50.00*+
None-2 unknown connection 480x640+0+0 0mm x 0mm
   480x640       65.74*+
root@letux:~# cat /sys/class/drm/card0-Unknown-*/enabled
enabled
enabled
root@letux:~# cat /sys/class/drm/card0-Unknown-*/status
unknown
unknown
root@letux:~# 

D) VENC patch but DPI returning connector_status_unknown

rroot@letux:~# xrandr
Screen 0: minimum 320 x 200, current 720 x 574, maximum 2048 x 2048
None-1 unknown connection
   480x640       65.74 +
None-2 connected 720x574+0+0 0mm x 0mm
   720x574i      50.00*+oot@letux:~# cat /sys/class/drm/card0-Unknown-*/enabled
disabled
enabled
root@letux:~# cat /sys/class/drm/card0-Unknown-*/status
unknown
connected

In case B) I have no TV out and in case D) I have no LCD.

So it looks as if it works if my LCD and VENC report the same
connection status. And fails if they differ.

Anyone with an explanation or even vague idea where to search
for the real bug?

BR and thanks,
Nikolaus