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

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi William,

On Friday 04 January 2013 11:52:28 William Swanson wrote:
> > 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.

What do you get in the memory buffers ? Are fields captured in separate 
buffers or combined in a single buffer ? If they're combined, are they 
interleaved or sequential in memory ?

> 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.

-- 
Regards,

Laurent Pinchart