[Openchrome-devel] Fix vt1625 output sensing

Willem van Asperen willem at van.asperen.org
Thu Nov 22 15:40:54 PST 2012

On 11/22/2012 02:28 PM, Xavier Bachelot wrote:
> Hi Harry,
> On 11/22/2012 02:01 PM, Harry de Boer wrote:
>> Hi,
>> I recently upgraded my Via machine to the latest Ubuntu and I couldn't
>> get my tv-output to work again. Last night I decided to dive into the
>> code a bit. The first thing I noticed was that vt1625 output sensing
>> seemed broken. Attached is a patch that should fix that.
>> I haven't got it working again yet so there's more to be done. If there
>> is anything I should know before continuing or have any tips please let
>> me know.
> Thanks for the patch. There's someone with issue with the TV out on an 
> EX board on the -users mailing list and he has trouble with probing the 
> TV out too, so it comes right to the point ;-)
I've applied Harry's patch and it now correctly senses the TV-Out, so
good work Harry!
The Xorg.0.log looks like:
||[ 88186.913] (II) CHROME(0): ViaOutputsDetect||
||[ 88186.913] (==) CHROME(0): LVDS-0 : Digital output bus width is 12
||[ 88186.913] (==) CHROME(0): LVDS-0 : DVI Center is disabled.||
||[ 88186.913] (==) CHROME(0): LVDS Panel will not be forced.||
||[ 88186.913] (==) CHROME(0): Panel size is not selected from config
||[ 88186.913] (II) CHROME(0): Output VGA-1 using monitor section Monitor0||
||[ 88186.914] (II) CHROME(0): ViaVT162xDetect||
||[ 88186.914] (II) CHROME(0): I2C device "I2C bus 2:VT162x" registered
at address 0x40.||
||[ 88186.915] (--) CHROME(0): Detected VIA Technologies VT1625 TV
Encoder||  <---- do we have a VT1625?
||[ 88186.915] (II) CHROME(0): ViaVT162xInit||
||[ 88186.915] (II) CHROME(0): Output TV-1 has no monitor section||
||[ 88186.915] (II) CHROME(0): VT162xSave||
||[ 88187.015] (II) CHROME(0): I2C device "I2C bus 1:ddc2" registered at
address 0xA0.||
||[ 88187.022] (--) CHROME(0): Test for CRT with VSYNC||
||[ 88187.023] (II) CHROME(0): EDID for output VGA-1||
||[ 88187.023] (II) CHROME(0): Printing probed modes for output TV-1||
||[ 88187.023] (II) CHROME(0): Modeline "640x480"x63.8   30.00  640 688
744 784  480 488 495 600 -hsync -vsync (38.3 kHz UdP)||
||[ 88187.023] (II) CHROME(0): Output VGA-1 disconnected||
||[ 88187.023] (II) CHROME(0): Output TV-1 connected  ||<---- RESULT!||
||[ 88187.023] (II) CHROME(0): Using user preference for initial modes||
||[ 88187.023] (II) CHROME(0): Output TV-1 using initial mode 640x480||
||[ 88187.023] (II) CHROME(0): VIAFreeScreen||
||[ 88187.023] (II) CHROME(0): VIAUnmapMem||
||[ 88187.026] (II) CHROME(0): VIAFreeRec||
||[ 88187.026] (II) CHROME(0): I2C device "I2C bus 2:VT1625" removed.|

But, alike my (feeble) attempt when I just forced the TV-Out to state
connected, this is where the log ends and X just disappears.

> There are 2 variant of the VT1625 (VT1625 and VT1625S) out in the wild 
> and it seems there are subtle differences between them. One of the 
> difference is one has 4 DACs and the other has 6. They are sharing the 
> same idea so I don't know of a good way to tell one from the other.
> Fortunately, there are datasheets available for both, it might help you 
> get the TV out working.
> See http://www.openchrome.org/trac/wiki/Development#TVencoders
> Out of curiosity, I do have an EX board too (for testing purpose) and 
> mine is using a VT1625S. What's the flavor on yours ?
>From the log I tend to think mine is a VT1625, no "S". But I might be

One more thing I noticed in the log:

||[ 88186.912] (**) CHROME(0): TV Type is PAL.||
||[ 88186.912] (**) CHROME(0): TV Output Signal is S-Video.||
||[ 88186.912] (==) CHROME(0): No default TV output port is set.||  <--- so?

Could this be an issue? And if so, how to fix this? I have set the BIOS
to use TV only and only enabled the S-Video output.

Finally, my xorg conf says:
||Section "Monitor"||
||  Identifier "Monitor0"||
||  HorizSync 30 - 50||
||  VertRefresh 50.0 - 50.0||
||Section "Device"||
||  Identifier "Device0"||
||  Driver "openchrome"||
||  Option "ActiveDevice" "TV"||
||  Option "TVType" "PAL"||
||  Option "TVOutput" "S-Video"||
||Section "Screen"||
||  Identifier "Screen0"||
||  Device "Device0"||
||  Monitor "Monitor0"||
||  SubSection "Display"||
||    Viewport 0 0||
||    Modes "720x576" "720x576Noscale"||
||  EndSubSection||

Yet, the X log, as you can see above, says:
||[ 88186.915] (II) CHROME(0): Output TV-1 has no monitor section||
But it does...

|[ 88994.747] (II) CHROME(0): Output TV-1 using initial mode 640x480|

Which should be 720x576, the PAL mode, as indicated in the conf.

Hope this helps. If there is anything more I can test, please let me know!

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