Re: [patch 5/5] saa7121 driver for s6000 data port

["Daniel Glöckner" <dg@emlix.com>]

On 03/30/2009 12:03 PM, Hans Verkuil wrote:
> What exactly do you need? If there is something missing, then it should be 
> added. But my guess is that you can pass such information via the s_routing 
> callback. That's what all other drivers that use v4l2_subdev do.

The s_routing callback looks very limited. One can pass only two u32 values.

The parameters that have to be negotiated are:
- What is the on-wire video format?
- how many data lines are connected?
- synchronization using embedded SAV/EAV codes or using dedicated pins?
- polarity of sync lines?
- valid CRC and line number in digital blanking?
- what is the layout of the digital image?
- how many odd lines are there? how many even? (including blanking)
- how many horizontal pixels? (incl. blanking)
- where is the active region?
- on which pixels/lines do we start/end horizontal/vertical sync?

>> It seems the soc-camera framework is a better choice here, but to make it
>> work with the saa7121 one would first have to implement support for video
>> output.
> 
> This framework will also be converted to use v4l2_subdev for the 
> communication with i2c drivers.

So it shouldn't matter which one I chose?

> Actually, I recommend that you first look at the existing saa7127.c source.
> I don't know how many differences there are between the saa7121 and 
> saa7127, but perhaps support for the saa7121 can be added there rather than 
> introducing a new driver. Of course, that only works if the differences are 
> not too big.

The chips appear to be very similar, sharing most of the registers. However, the
aforementioned problem still exists with this driver. A driver connecting this
sub device must know beforehand that it has to send standard BT.656 video frames
with SAV/EAV codes.

  Daniel


-- 
Dipl.-Math. Daniel Glöckner, emlix GmbH, http://www.emlix.com
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