Hi,
On Tuesday 17 December 2013 05:19 PM, Hans Verkuil wrote:
On 12/17/13 12:19, Archit Taneja wrote:
Hi Hans,
On Tuesday 17 December 2013 01:30 PM, Hans Verkuil wrote:
On 12/12/2013 09:35 AM, Archit Taneja wrote:
The VPE and VIP IPs in DRA7x contain common scaler and color
conversion hardware blocks. We create libraries for these
components such that the vpe driver and the vip driver(in future)
can use these library funcs to configure the blocks.
There are some points for which I would like comments:
- For VPE, setting the format and colorspace for the source and
destination queues is enough to determine how these blocks need
to be configured and whether they need to be bypassed or not. So
it didn't make sense to represent them as media controller
entities. For VIP(driver not upstream yet), it's possible that
there are multiple data paths which may or may not include these
blocks. However, the current use cases don't require such
flexibility. There may be a need to re-consider a media
controller like setup once we work on the VIP driver. Is it a
good idea in terms of user-space compatibilty if we use media
controller framework in the future.
As long as you don't need the mc, then there is no need to
implement it.
The thing is that we want to use these blocks for a future capture
hardware called VIP. A VIP port can capture multiple streams from
different sensors in time slices, and each of those streams might be
sharing the same hardware, but probably in different configurations.
I'm not completely aware of media controller details, and whether it
can help us here.
I was just wondering if it would be a problem if we later realise
that mc might be useful for some use cases. Would implementing it
then break previous user space applications which don't call mc
ioctls?
My understanding is that in the current vpe driver the mc won't be
needed, so there is no point adding it. When implementing the vip
capture driver the mc might be needed, but that should not require
the vpe to add the mc API as well. It's a decision that has to be
made per driver.
That's right, vpe doesn't need mc. It might be needed for vip. The
reason I brought it up now is because some of the blocks like SC/CSC are
replicated in VIP hardware, and I created them in a 'library' sort of
way in this series. If vip driver uses mc, these blocks might need to
become media entities.
When you start work on the vip driver it is probably a good idea to
talk to Laurent and myself first to see whether the mc is needed or
not.
Thanks, that'll be quite useful. I'll look up some mc documentation and
drivers using mc myself as well.
If you have a block diagram of the video hardware that you can share,
then that will be quite useful.
Thanks for the clarification. I don't think the DRA7x documentation is
public yet. I'll try to look for a block diagram(or create one) and
share it with the list.
Archit
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