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--- en:c2_forcergb [2016/12/15 15:18]
joy.cho created
+++ en:c2_forcergb [2016/12/20 07:46] (current)
joy.cho [HDMI Force RGB Option]
@@ Line 1: / Line 1: @@
-(under construction)
+========= HDMI Force RGB Option =======
+<WRAP center round important>
+  * Ubuntu : The available version should be the one released after Jun 20, 2016.
+  * Android : Android Marshmallow v1.2 (Dec 19, 2016) or higher version is available.
+</WRAP>
+===== Issue Brief =====
+With some TV monitors, there is a bug in their HDMI implementation that sometimes trigger the selection of the wrong colorspace in a magenta/green display.\\
+{{:en:c2_forcergb_1.png?600}} \\
+http://forum.odroid.com/viewtopic.php?f=141&t=20697#p137351
+It looks TV reports that is capable of YUV422 or YUV444 but it's not indeed.\\
+To avoid this situation, you can use **forcergb** option to set COLORSPACE_SPACE_RGB444 forcibly.
+Here are more investigations and discussions in ODROID Forum.
+  * http://forum.odroid.com/viewtopic.php?f=144&t=21780&hilit=forcergb
+  * http://forum.odroid.com/viewtopic.php?f=141&t=21737
+  * http://forum.odroid.com/viewtopic.php?f=144&t=20415&p=145208#p145208
+===== How to set boot.ini to activate forcergb =====
+To activate it, add **hdmitx=forcergb** in bootargs.
+<code>
+setenv bootargs ${bootargs} hdmitx=forcergb
+</code>
+Here is the catch.\\
+The env **hdmitx** has other parameters related to HDMI CEC control.\\
+If you use CEC options, the env format can be **hdmitx=cecf,forcergb** or **hdmitx=cec0,forcergb**.\\
+The ODROID Forum user, wrxtasy from LibreELEC already implemented a good guide for this case.\\
+https://github.com/wrxtasy/LibreELEC.tv.7.0/blob/libreelec-7.1/projects/Odroid_C2/bootloader/boot.ini
+<code>
+# Enable | Disable HDMI CEC Control
+setenv hdmi_cec  "0"            # Disabled
+# setenv hdmi_cec  "1"          # Enabled
+# setenv hdmi_cec  "2"          # Enabled but disable auto TV switching ON
+# Force HDMI to use RGB colorspace regardless of TV request
+# setenv hdmi_forcergb "0"      # Disabled
+setenv hdmi_forcergb "1"        # Enabled
+if test "${hdmi_cec}" = "0"; then setenv hdmitx "hdmitx=cec0"; fi
+if test "${hdmi_cec}" = "1"; then setenv hdmitx "hdmitx=cecf"; fi
+if test "${hdmi_cec}" = "2"; then setenv hdmitx "hdmitx=cec7"; fi
+if test "${hdmi_forcergb}" = "1"; then setenv hdmitx "${hdmitx},forcergb"; fi
+setenv bootargs "${rootopt} ${consoleopt} hdmimode=${hdmimode} ${hdmitx} vout=${vout_mode} ............"
+</code>