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iMX6Q: Empty buffers capturing sensor data (Aptina MT9V126)

Question asked by Andre W. on Apr 15, 2014
Latest reply on Apr 24, 2014 by Andre W.

Hi All,


I am currently trying to grab images from a Aptina MT9V126 sensor on iMX6 Q. Kernel is based on

Freescales Linux-3.0.35-fsl-4.1. The sensor driver is based on a driver provided by Aptina for the

MT9V129 and is adapted to our needs.


Sensor output format:

     640 x 480 framesize

     YCbCr progessive

     30 Hz framerate


After initialization the driver offers a sensor device on /dev/video0. The sensor is correctly configured

via I²C: sensor streams with correct rates of line- and framesync (I can see a framerate of 30Hz on

the oscilloscope). Data pins are also showing a plausible signal.


I do have a user space application that accesses /dev/video0 and uses the V4L2-Api to access

sensor data. Setting up format, querying and queueing buffers works fine. After start of capture and

when polling the sensor filedescriptor, poll function regularily returns at a rate of 30 times per second

(which matches framerate). I can also dequeue and requeue the buffers.


My problem is: the buffers that return from the V4L layer are not filled with sensor data. All bytes are

zero or contain data I have written into the buffers before queing them.


Any suggestions?