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[android-kernel] USB camera node not getting created on few Android tablets sandeep mantrala Mon Feb 06 10:03:24 2012

Hi all,

When an USB camera is connected to Android tablet, in some tablets node is
getting created and in some others node is not getting created.

When I connect USB camera to Acer Iconia tablet, /dev/video1 is created,
but it does not gets created in Samsung Galaxy tab. In Acer, using this
node i designed an application that uses this node and fetches a frame from
the camera. My application calls UVC firmware( peice of code that calls
v4l2 layer through standard ioctl calls) that calls v4l2 layer and then it
fetches the frames from the real Hardware.
Now I am trying to find out the exact reason why the node is not getting
created in Samsung galaxy tab. Kindly share with me the following details.

Kindly share any knowledge that you have in creation of node. In case i
find out the answers myself, i will reply back with my findings. In all the
following cases, If files(code) that are responsible are pointed out from
source code it would be really great.

   - Once i connect a USB Camera how does the system know that a Camera is
   inserted and what are the steps it follows from then on?
   - Who creates the device node(Driver or daemon or something else)? It
   would be really great if particular files in source code are pointed out
   that makes the situation more clear.
   - I tried doing mknod /dev/video1 c 81 0(81 and 0 are the major and
   minor numbers in Acer tablet). But my application isnt able to open the
   node.(I think the reason is that though i created a node, there is no open
   method registered for the node.)How should i associate a driver with my new
   node that i am creating. If i am missing out on some basic thing, please
   let me know.

Final goal is to create a node on Samsung galaxy tab aswell. I have source
code of galaxy tab that i downloaded from opensource.samsung.com

Thanks for spending time in reading my mail. Hope to see some replies for
my problem.

Thanks & Rgds,

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