SupaCEC - A utility to switch TV inputs when a controller is connected

Hex

@superterran What is the use for this? Of what I know retropie already switches on my TV and sets source to itself while booting up

Sano

@Hex
Precisely, only when booting up (or launching kodi).
Given the power consumption of the RPi, I suppose many people just let it powered on 24/7, and I'm one of them :)
So I have to switch the amp input everytime I want to play, so this script could be really handy for people like me. I'll take a look.
Thx @superterran

Sano

Ok, took a look, some interesting hints on CEC management.
But the daemon mode with an infinite loop is bothering me.
I'm currently making some tests to generate an udev rule that execute the right cec commands when an new input device is detected.
It should be cleaner :)

superterran

@Sano Very nice, I didn't really like my approach either but didn't want to go down the road of installing inotify-tools and this way seemed good enough for the purposes of a proof of concept.

@robertybob so what this does is scan for new input devices like joysticks and keyboards to be detected by the system, and it will trigger a CEC command that will direct your TV to switch inputs to the RetroPie. The usecase here is if your sitting on your couch, your TV is off or on another input, you can interact with the controller and the TV will either change inputs or turn on the TV. If you were watching a movie on your Chromecast, it will pause the movie first.

godhunter74

Hi very Nice job
It will be interesting to add some feature like :

turn off tv when ES is sleeping instead off screensaver
Turn on TV when ES Wake up
display name of rom playing in cec name osd
Maybe some others tools il you have more idea

superterran

I'm interested to see if @Sano made any progress, I might explore his route too as I know the loop is no good. In terms of @godhunter74's feedback I really like the notion of firing this when ES is waking up, I'll explore that a bit - maybe that's a better idea than listening? Personally, I'd like to add a controller hotkey to modify the TV volume, this would be huge in my household and would improve my whole entertainment center.

Sano

Ah yes sorry, didn't had much time the few past days.
The udev rule was quite simple :
ACTION=="add", SUBSYSTEM=="input", RUN+="echo 'as' | cec-client -s -d 1"

Unfortunately, the RUN primitive of udev rules seems not to apply since systemd.
I wasted an entire evening to understand that by testing :)
Then I found this thread :
https://retropie.org.uk/forum/topic/3335/anyone-familiar-with-udev-rules

It should be possible to circumvent this via the use of a systemd daemon script.

Maybe @mediamogul can help us on this one, as he faced the same issu ?

psyke83

@Sano said in SupaCEC - A utility to switch TV inputs when a controller is connected:

ACTION=="add", SUBSYSTEM=="input", RUN+="echo 'as' | cec-client -s -d 1"

No, I think the problem is that udev doesn't parse pipe or redirects as it doesn't run a shell but passes arguments literally. If you use "/bin/sh -c 'commands'" it should process pipes and redirections correctly.

Sano

Thanks, but I also tried to call a simple shell script with the command line and, it was not working either...
So seeing @mediamogul post I thought udev/systemd was indeed the problem...

psyke83

Yes, it's not working, but I did try: "/usr/bin/touch ~/test", and it worked, so the RUN argument is not fully deprecated.

There are existing udev scripts in retropie that run commands directly, and I even added my own to control disk spindown via smartctl, so it does work... I'm betting the problem is the pipe.

Sano

@psyke83
Roger that, but why my call to a (working) sh script didn't work ?
And why does a simple touch works ? Strange AF...

Plus there are a lot of this kind of docs highlighting the need of a systemd script in order to launch anything... https://fixmynix.com/run-shell-scripts-from-udev-rules/

psyke83

I got it to work like so:

ACTION=="add", SUBSYSTEM=="input", RUN+="sh -c /home/pi/waketv.sh"

waketv.sh:
#!/bin/sh
/bin/sh -c 'echo 'as' | cec-client -s -d 1'

I'll see if there's a way to make the pipe work without relying on a script.

Sano

@psyke83
Congrats !
That said, even with your syntax I can't make it work on my setup :(
Maybe something is messed up on my RPi...

mediamogul

@Sano

Maybe @mediamogul can help us on this one, as he faced the same issu ?

Sorry, I'm just now seeing this. Unfortunately, I was never able to get further than what was posted in that original thread. I'm glad it's being revisited and that there might be a working option.

psyke83

@Sano

This should work:

ACTION=="add", SUBSYSTEM=="input", RUN+="/bin/bash -c 'echo 'as' | cec-client -s -d 1'"

I actually tested this (as someone else is using the tv):
ACTION=="add", SUBSYSTEM=="input", RUN+="/bin/bash -c 'echo test | tee /dev/kmsg'"

For some reason, "test" is echoed three times to the kernel log & I'm not certain precisely why...

Sano

@psyke83 said in SupaCEC - A utility to switch TV inputs when a controller is connected:

This should work:

ACTION=="add", SUBSYSTEM=="input", RUN+="/bin/bash -c 'echo 'as' | cec-client -s -d 1'"

Sorry, still no luck :(
But thanks a lot for trying !

For some reason, "test" is echoed three times to the kernel log & I'm not certain precisely why...

That I know :)
just run an sudo udevadm monitor -e before pluging anything
It's just the kernel and udev adding the new device, link, driver,... (depends on the device)
Easy to filter in the rules, if only the RUN primitive could work as intented...

@mediamogul thanks for reading and answering anyway. Hope we'll find a clean solution. @psyke83 seems to be the man.

psyke83

@Sano said in SupaCEC - A utility to switch TV inputs when a controller is connected:

ACTION=="add", SUBSYSTEM=="input", RUN+="/bin/bash -c 'echo 'as' | cec-client -s -d 1'"

OK, I commandeered the TV to test and can confirm it didn't work ;). However, the pipe is working via the tee command, so the problem might be due to the cec-client being called three times in succession. Can you try refining the rule and testing? Also test "tee >/dev/kmsg" just to make sure there's no difference in configuration between our systems.

Edit: also, try specifying the path of cec-client in the command just in case the PATH is not initialized properly.

psyke83

OK, this definitely works! ;)

ACTION=="add", SUBSYSTEM=="input", RUN+="/bin/bash -c 'echo as | /usr/bin/cec-client -s -d 1'"

The problem was either the nested apostrophes or missing PATH. I don't want to annoy the person watching the tv, so you'll need to test, but the above line worked for me. I assume it executed the command three times, however, so refining is a good idea.

This filter works for my DS3 controller causing it to execute once:
ACTION=="add", SUBSYSTEM=="input", KERNEL=="js[0-9]*", RUN+="/bin/bash -c 'echo as | /usr/bin/cec-client -s -d 1'"

Sano

Ok finally found a simple solution working here, if anybody could test :

First install cec-utils :
sudo apt-get install cec-utils

Create a /etc/udev/rules.d/10-cec.rules with this line:

ACTION=="add", KERNEL=="js0", SUBSYSTEM=="input", RUN+="/bin/bash -c '/bin/echo as | /usr/bin/cec-client -s -d 1'"

Note the rule will match only for the first controller (js0) and execute only once, and also note the full path to binaries.

Reload udev rules :
sudo udevadm control --reload-rules

When you plug the first controller, the tv should switch to retropie.
I tested it with (wireless) PS3 controller and USB arcade stick.

@psyke83
I was so concentrated testing things that I missed your post. Congrats, you found it first :)
The good thing is we both came to the same conclusions.

superterran

Awesome @Sano and @psyke83! I haven't had a chance to test this yet, but I like where this was headed and wanted to formalize something. I'll hopefully test it tonight, in the meantime if anyone wants to look it over https://github.com/superterran/SupaCEC/tree/refactoring-to-udev-rule