[PATCH] Add RGB555X and RGB565X formats to pxa-camera

[Guennadi Liakhovetski]

On Sat, 5 Sep 2009, Marek Vasut wrote:

> > > >  drivers/media/video/pxa_camera.c |    4 ++++
> > > >  1 files changed, 4 insertions(+), 0 deletions(-)
> > > >
> > > > diff --git a/drivers/media/video/pxa_camera.c
> > > > b/drivers/media/video/pxa_camera.c
> > > > index 46e0d8a..de0fc8a 100644
> > > > --- a/drivers/media/video/pxa_camera.c
> > > > +++ b/drivers/media/video/pxa_camera.c
> > > > @@ -1222,6 +1222,8 @@ static int required_buswidth(const struct
> > > > soc_camera_data_format *fmt)
> > > >  	case V4L2_PIX_FMT_YVYU:
> > > >  	case V4L2_PIX_FMT_RGB565:
> > > >  	case V4L2_PIX_FMT_RGB555:
> > > > +	case V4L2_PIX_FMT_RGB565X:
> > > > +	case V4L2_PIX_FMT_RGB555X:
> > > >  		return 8;
> > > >  	default:
> > > >  		return fmt->depth;
> > > > @@ -1260,6 +1262,8 @@ static int pxa_camera_get_formats(struct
> > > > soc_camera_device *icd, int idx,
> > > >  	case V4L2_PIX_FMT_YVYU:
> > > >  	case V4L2_PIX_FMT_RGB565:
> > > >  	case V4L2_PIX_FMT_RGB555:
> > > > +	case V4L2_PIX_FMT_RGB565X:
> > > > +	case V4L2_PIX_FMT_RGB555X:
> > > >  		formats++;
> > > >  		if (xlate) {
> > > >  			xlate->host_fmt = icd->formats + idx;
> 
> What should we do with this patch? Any updates? I spoke to Guennadi and he 
> thinks it's not a good idea to apply it (as pxaqci doesnt support those 
> formats). But to my understanding, those formats are endian-swapped versions of 
> the other ones without X at the end so there shouldnt be a problem with it.

Marek, please, look in PXA270 datasheet. To support a specific pixel 
format means, e.g., to be able to process it further, according to this 
format's particular colour component ordering. Process further can mean 
convert to another format, extract various information from the data 
(statistics, etc.)... Now RGB555 looks like (from wikipedia)

15  14  13  12  11  10  09  08  07  06  05  04  03  02  01  00
R4  R3  R2  R1  R0  G4  G3  G2  G1  G1  B4  B3  B2  B1  B1  --

(Actually, I thought bit 15 was unused, but it doesn't matter for this 
discussion.) Now, imagine what happens if you swap the two bytes. I don't 
think the PXA will still be able to meaningfully process that format.

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/