On 10/19/18 2:53 AM, Philipp Zabel wrote:
Hi Tim,
On Thu, 2018-10-18 at 15:53 -0700, Tim Harvey wrote:
[...]
Philipp,
Thanks for submitting this!
I'm hoping this lets us use non-IMX capture devices along with the IMX
media controller entities to so we can use hardware
CSC,scaling,pixel-format-conversions and ultimately coda based encode.
I've built this on top of linux-media and see that it registers as
/dev/video8 but I'm not clear how to use it? I don't see it within the
media controller graph.
It's a V4L2 mem2mem device that can be handled by the GstV4l2Transform
element, for example. GStreamer should create a v4l2video8convert
element of that type.
The mem2mem device is not part of the media controller graph on purpose.
There is no interaction with any of the entities in the media controller
graph apart from the fact that the IC PP task we are using for mem2mem
scaling is sharing hardware resources with the IC PRP tasks used for the
media controller scaler entitites.
It would be nice in the future to link mem2mem output-side to the ipu_vdic:1
pad, to make use of h/w VDIC de-interlace as part of mem2mem operations.
The progressive output from a new ipu_vdic:3 pad can then be sent to the
image_convert APIs by the mem2mem driver for further tiled scaling, CSC,
and rotation by the IC PP task. The ipu_vdic:1 pad makes use of pure
DMA-based
de-interlace, that is, all input frames (N-1, N, N+1) to the VDIC are sent
from DMA buffers, and this VDIC mode of operation is well understood
and produces clean de-interlace output. The risk is that this would require
iDMAC channel 5 for ipu_vdic:3, which IFAIK is not verified to work yet.
The other problem with that currently is that mem2mem would have to be
split into
separate device nodes: a /dev/videoN for output-side (linked to
ipu_vdic:1), and
a /dev/videoM for capture-side (linked from ipu_vdic:3). And then it no
longer
presents to userspace as a mem2mem device with a single device node for both
output and capture sides.
Or is there another way? I recall work to integrate mem2mem with media
control.
There is v4l2_m2m_register_media_controller(), but that create three
entities:
source, processing, and sink. The VDIC entity would be part of mem2mem
processing but this entity already exists for the current graph. This
function
could however be used as a guide to incorporate the VDIC entity into m2m
device.
Steve
