[RFC] [media] imx: assume MEDIA_ENT_F_ATV_DECODER entities output video on pad 1

[Mauro Carvalho Chehab]

Em Wed, 5 Apr 2017 11:39:06 -0400
Devin Heitmueller <dheitmueller at kernellabs.com> escreveu:

> > Currently, the driver doesn't support (2), because, at the time
> > I wrote the driver, I didn't find a way to read the interrupts generated
> > by tvp5150 at em28xx[1], due to the lack of em28xx documentation,
> > but adding support for it shoudn't be hard. I may eventually do it
> > when I have some time to play with my ISEE hardware.  
> 
> For what it's worth, I doubt most of the em28xx designs have the
> tvp5150 interrupt request line connected in any way.

True. But, on embedded hardware, such line may be connected into the
SoC. Actually, from the IGEPv3 expansion diagram:

	https://www.isee.biz/support/downloads/item/igepv2-expansion-rc-schematics

The INT line is connected to CAM_IRQ. That's connected to GPIO_154 pin
at OMAP3.

So, on a first glance, it seems possible to use it, instead of polling.

> You would likely
> have to poll the FIFO status register via I2C,

Yes, I considered this option when I wrote the driver. It could work, 
although it would likely have some performance drawback, as the driver
would need to poll it at least 60 times per second.

> or use the feature to
> embed the sliced data into as VANC data in the 656 output (as
> described in sec 3.9 of the tvp5150am1 spec).

True, but the bridge driver would need to handle such data. 

I remember I looked on this when I wrote the driver, but I was
unable to find a way for em28xx to parse (or forward) such
data packets.

Thanks,
Mauro