dddvb/docs/redirect

NOTE: This is an unsupported hack so that legacy software works
      with the hardware!
      To properly pass data through a CI CAM you should read
      the TS from a dvr device and write it to a ci device
      in user space!

Redirection of TS streams through CI modules is now supported 
through /sys/class/ddbridge/ddbridge0/redirect.
It only works with cards based on the ddbridge PCIe bridge, not
with nGene based cards.

It is set up in such a way that you can write "AB CD" to
a "redirect" attribute and data from input B of card A is then piped through
port D (meaning TAB (D+1) which uses output D and input 2*D for CI io)
of card C and then shows up in the demux device belonging to
input B (input (B&1) of TAB (B/2+1)) of card A.

E.g.:

echo "00 01" > /sys/class/ddbridge/ddbridge0/redirect

will pipe input 0 of card 0 through CI at port 1 (TAB 2) of card 0.

Redirection should only be done right after loading the driver 
(or booting if the driver is built-in) and before using the
devices in any way.

adapter_alloc=3 is rcommended when using redirect
The ci device will then show up in the same adapter directory and most
software will then assume it belongs to the frontend in the same directory.


Redirect between cards in different IOMMU groups will not work!
Disable IOMMU if you have this problem.