VPIF configuration for raw capture

We are using a omapL138 EVM from calixto and interfaced an Omnivision 2MP sensor.
We are trying to capture a RAW image(1600x1200 ,UXGA(RAW) 7.5fps) via the VPIF input
interface using the sample vpif capture application(vpif loopback application provided by TI).
The application is modified to do only the capture functionality and have shunted all the
display related functionality.
we are able to config the camera and initialize to output RAW data and the camera data
output shows valid data , hsync and vsync as per the configuration(verified using oscilloscope).

Procedure:
==========
[1] Probe and detect the camera on the i2c interface.
[2] Initialize the camera module for outputting a RAW format [1600x1200 7.5 fps].
[3] Run the modified capture application.

VPIF register configuration:
============================
VPIF_CH0_CTRL = 0x281405  ( 8 bit/pixel, frame based storage,progressive format,top field vsync only)
VPIF_CH1_CTRL = 0x405
VPIF_INTEN = 0x13
VPIF_INTEN_SET = 0x13
VPIF_INTEN_CLR = 0
VPIF_STATUS = 0
VPIF_REQ_SIZE = 0x100
VPIF_CH0_TOP_STRT_ADD_LUMA = 0xc8600000
VPIF_CH0_BTM_STRT_ADD_LUMA = 0xc8600640
VPIF_CH0_IMG_ADD_OFST = 0x640

Issue:
========
[1] However when the sample application attempts to de-queues the captured buffer from the
capture device's outgoing queue it does not respond and the data is not seen in the capture buffer.

Observation:
============
[1] In the vpif capture driver the vpif_channel_isr() API is not getting invoked even with the valid data
vsync,hsync is available from the camera.

Query :
=======
[1] Does the VPIF configuration match for the kind of RAW capture I am trying to do?
[2] Is there any additional configuration that needs to be done in the application side / vpif capture
 driver to capture RAW data?.