[media] vivid: add CEC emulation

The vivid driver has been extended to provide CEC adapters for the HDMI
input and HDMI outputs in order to test CEC applications.

This CEC emulation is faithful to the CEC timings (i.e., it all at a
snail's pace).

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 31 insertions, 5 deletions

diff --git a/Documentation/video4linux/vivid.txt b/Documentation/video4linux/vivid.txt
index 8da5d2a576bc..1b26519c6ddc 100644
--- a/Documentation/video4linux/vivid.txt
+++ b/Documentation/video4linux/vivid.txt
@@ -74,7 +74,8 @@ Section 11: Cropping, Composing, Scaling
 Section 12: Formats
 Section 13: Capture Overlay
 Section 14: Output Overlay
-Section 15: Some Future Improvements
+Section 15: CEC (Consumer Electronics Control)
+Section 16: Some Future Improvements
 
 
 Section 1: Configuring the driver
@@ -364,7 +365,11 @@ For HDMI inputs it is possible to set the EDID. By default a simple EDID
 is provided. You can only set the EDID for HDMI inputs. Internally, however,
 the EDID is shared between all HDMI inputs.
 
-No interpretation is done of the EDID data.
+No interpretation is done of the EDID data with the exception of the
+physical address. See the CEC section for more details.
+
+There is a maximum of 15 HDMI inputs (if there are more, then they will be
+reduced to 15) since that's the limitation of the EDID physical address.
 
 
 Section 3: Video Output
@@ -409,6 +414,9 @@ standard, and for all others a 1:1 pixel aspect ratio is returned.
 
 An HDMI output has a valid EDID which can be obtained through VIDIOC_G_EDID.
 
+There is a maximum of 15 HDMI outputs (if there are more, then they will be
+reduced to 15) since that's the limitation of the EDID physical address. See
+also the CEC section for more details.
 
 Section 4: VBI Capture
 ----------------------
@@ -1108,7 +1116,26 @@ capabilities will slow down the video loop considerably as a lot of checks have
 to be done per pixel.
 
 
-Section 15: Some Future Improvements
+Section 15: CEC (Consumer Electronics Control)
+----------------------------------------------
+
+If there are HDMI inputs then a CEC adapter will be created that has
+the same number of input ports. This is the equivalent of e.g. a TV that
+has that number of inputs. Each HDMI output will also create a
+CEC adapter that is hooked up to the corresponding input port, or (if there
+are more outputs than inputs) is not hooked up at all. In other words,
+this is the equivalent of hooking up each output device to an input port of
+the TV. Any remaining output devices remain unconnected.
+
+The EDID that each output reads reports a unique CEC physical address that is
+based on the physical address of the EDID of the input. So if the EDID of the
+receiver has physical address A.B.0.0, then each output will see an EDID
+containing physical address A.B.C.0 where C is 1 to the number of inputs. If
+there are more outputs than inputs then the remaining outputs have a CEC adapter
+that is disabled and reports an invalid physical address.
+
+
+Section 16: Some Future Improvements
 ------------------------------------
 
 Just as a reminder and in no particular order:
@@ -1121,8 +1148,6 @@ Just as a reminder and in no particular order:
 - Fix sequence/field numbering when looping of video with alternate fields
 - Add support for V4L2_CID_BG_COLOR for video outputs
 - Add ARGB888 overlay support: better testing of the alpha channel
-- Add custom DV timings support
-- Add support for V4L2_DV_FL_REDUCED_FPS
 - Improve pixel aspect support in the tpg code by passing a real v4l2_fract
 - Use per-queue locks and/or per-device locks to improve throughput
 - Add support to loop from a specific output to a specific input across
@@ -1133,3 +1158,4 @@ Just as a reminder and in no particular order:
 - Make a thread for the RDS generation, that would help in particular for the
   "Controls" RDS Rx I/O Mode as the read-only RDS controls could be updated
   in real-time.
+- Changing the EDID should cause hotplug detect emulation to happen.