Re: [PATCH] omap3isp: Add support for interlaced input data

[William Swanson <william.swanson@fuel7.com>]

> Laurent Pinchart <laurent.pinchart@ideasonboard.com> escreveu:
>> On Monday 17 December 2012 18:12:19 William Swanson wrote:
>>> If the remote video sensor reports an interlaced video mode, the CCDC block
>>> should configure itself appropriately.
>>
>> What will the CCDC do in that case ? Will it capture fields or frames to
>> memory ? If frames, what's the field layout ? You will most likely need to
>> modify ispvideo.c as well, to support interlacing in the V4L2 API, and
>> possibly add interlaced formats support to the media bus API.

Sorry for the delay in responding; today is my first day back at the 
office. I do not know the answers to these questions, and the 
documentation doesn't discuss interlacing much. Our application has the 
following pipeline:

     composite video -> TVP5146 decoder
     -> CCDC parallel interface -> memory -> application

One of the wires in the parallel interface, cam_fld, indicates the 
current field, and this patch simply enables that wire. Without the 
patch, every other line in our memory buffer is garbage; with the patch, 
the image comes out correctly.

As a matter of fact, an earlier version of the ISP driver actually 
contained code for dealing with this flag; it was removed in 
cf7a3d91ade6c56bfd860b377f84bd58132f7a81 along with a bunch of other 
cleanup work. This patch simply adds the code back, but in a way that is 
compatible with the new media pipeline stuff.

I believe that the CCDC simply captures image data a line at a time and 
writes it directly to memory, at least in our use case. The CCDC_SDOFST
register controls the layout, and the default value (which is what the 
driver uses now) is basically correct. I am not familiar enough with the 
V4L2 architecture to tell you how the driver decides that it now has a 
complete frame, or what that even means in an interlaced case.

On 12/27/2012 12:27 PM, Mauro Carvalho Chehab wrote:
 > Btw, you missed to add a Signed-off-by: line on it.

Oops, this was a problem with my git setup. Both email addresses are 
mine; I can re-send the patch with them both set to the same address if 
you would prefer that.

-William