via-camera upstream test results

Jon Nettleton jon.nettleton at
Thu Oct 28 15:29:09 EDT 2010

On Thu, Oct 28, 2010 at 12:05 PM, Jonathan Corbet <corbet at> wrote:
>> 1. Approx 13 "VIA DMA timeout!" messages are printed every second
> That seems undesirable.  In the past there was trouble with the
> user-space xv code mucking around with the interrupt control registers,
> but I *thought* that had been fixed.

This has been fixed in the driver.  You should be able to test what is
triggering the problem by writing a gst-launch command from a VT that
writes the output to a dummy output.  If we don't get error messages
then this involves the DDX code.

>> 2. If you start a capture with "gst-launch v4l2src ! xvimagesink" then
>> change to a VT console then back to X, the display stops updating
>> properly - it seems to have locked itself onto a few frames from
>> before the VT switch happened, and plays them in an endless loop
>> Also happens with "gst-launch v4l2src ! ffmpegcolorspace ! ximagesink"
> I thought I had tried that, but, evidently not.  Something in the
> framebuffer switch code is clearly interfering with the video capture
> engine, it would be nice to figure out what that is.  If you're
> capturing to a file, you'd really want that to survive a switch.
> This will be something deep in the viafb code.

This may also be an interaction between the fb and the ddx drivers.
In the X driver when we Enter and Leave VT's we store and restore
registers.  We find some chipsets are picky about what you can and
can't touch when doing this.


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