Changes between Version 6 and Version 7 of linux/media

Timestamp:

02/20/2019 10:25:06 PM (6 years ago)

Author:

Tim Harvey

Comment:

added EDID section

linux/media

@@ -447 +447 @@
      rtph264pay ! udpsink host=$SERVER port=$PORT
 }}}
+
+
+
+[=#edid]
+== EDID
+HDMI sources require an EDID from the HDMI sink (ie monitor/capture device) to know what formats are allowed. This is done on v4l2 capture devices such as the tda1997x by using the 'v4l2-ctl --set-edid' on the subdev for the capture device. The capture device will then provide this to the HDMI source (it wiggles its HPD line which is the equivalent of a hotplug) and then the HDMI source will provide the sink (capture device) with something compatible which you can then query. You can provide either a raw EDID binary file or a type which will cause the kernel to auto-generate a compatible EDID from.
+
+Examples:
+ - show options for setting edid:
+{{{#!bash
+v4l2-ctl --help-edid
+}}}
+ - provide an EDID to the tda1997x by description:
+{{{#!bash
+v4l2-ctl -d $(media-ctl -e "tda19971 2-0048") --set-edid=type=hdmi
+}}}
+ - provide an EDID by binary file
+{{{#!bash
+v4l2-ctl -d $(media-ctl -e "tda19971 2-0048") --set-edid=file=edid.hex # hex
+v4l2-ctl -d $(media-ctl -e "tda19971 2-0048") --set-edid=file=edid.bin,format=raw # binary
+}}}
+ - clear the EDID:
+{{{#!bash
+v4l2-ctl -d $(media-ctl -e "tda19971 2-0048") --clear-edid
+}}}
+ - get edid
+{{{#!bash
+# show it in hex format
+v4l2-ctl -d $(media-ctl -e "tda19971 2-0048") --get-edid=format=hex
+# save it to a file
+v4l2-ctl -d $(media-ctl -e "tda19971 2-0048") --get-edid pad=0,file=edid.hex,format=hex # hex
+v4l2-ctl -d $(media-ctl -e "tda19971 2-0048") --get-edid file=edid.bin,format=raw # binary
+}}}
+
+Notes:
+ - the above commands do not provide the optional 'pad' argument as it defaults to pad 0 which is the only pad of the tda1997x