Pi 4 - Mouse support in RetroArch

MrLightgun

Hi Everyone

I tried the work in progress build on the Pi 4 as per the usual instructions a few weeks ago but RetroArch just refused to see my mouse devices, either normal USB mouse or Lightgun Mouse device. The mice are all viewable fine using /dev but when loading a RetroArch core they cannot be seen and also when I do logging there is no mention of the mice where it usually comes up.

I also changed the RetroArch input API to udev but that didn't fix it. I was sure that was going to be the issue when I found it wasn't set to udev but that didn't help. I tried a reinstallation too.

I feel like it is a permission issue but don't have the linux skills to diagnose and fix it. I did try adding various udev permissions but that didn't work. I also tried a few flags on the build strings but that didn't help either. The same devices all work fine in RetroArch on the 3B+.

Has anyone managed to get their mice to work in RetroArch on the Pi 4? Did you do anything special?

Best regards

Mr Lightgun

mitu

Mice do work on the PI4 - I just tested the scenario from the other topic (FCEumm and Duck Hunt) on the Pi4 and didn't have any issues.
Generally, Linux distributions nowadays are automatically setting permissions on /dev devices so you don't have to fiddle with it, so I don't think that's an issue here. As long as your account is part of the input group, that's ok (the default Raspbian - pi - user is already set-up with the proper permissions).

Are you using the a 'stock' RetroArch version or the one distributed through the RetroPie setup script (1.7.1) ? Did you add any patches/have any custom developments on the source ? (I know you've sent some patches upstream, that's why I'm asking).

For the record, I'm using the 1.7.9.2 installed through this PR.

MrLightgun

Hi @mitu

Thank you for the reply. That is good news. The fact it works for you without you doing anything special gives me hope I just did something I shouldn't. I will try again and keep it as simple as possible, making sure stock works before attempting any patches. I think your theory is probably correct or I typed one of the build commands wrong. At the time I just assumed the functionality wasn't there yet.

At least that way if I have any issues I can be clearer on what I have done.

Best regards

Mr Lightgun

MrLightgun

Hi @mitu

So the good thing is that the mouse worked so I obviously broke it previously trying to update RetroArch. The thing is there are bugs in RetroArch I need to fix for my stuff to work correctly. Running your 1.7.9.2 would help because that version has the 2 biggest show stoppers fixed but I do have a 3rd which is not yet committed.

I want to manually install RetroArch with my bug fixes. I followed the instructions from here:
https://retropie.org.uk/forum/topic/16926/retroarch-cores-crash-on-trigger-press-mouse-click-with-overlay-active/28
In the post by SuperJim at 6 Mar 2019, 08:03

However his instructions rely on the correct build flags which I obviously failed to get correct on the Pi 4. Could you tell me what the correct CFLAGS are for the Pi 4 at this step or if there is an alternative way to change a RetroArch release. I have my own branch but I can't change a release.

Thanks

Mr Lightgun

mitu

I'm not sure how you're building your RetroArch branch, but to get RetroPie to compile it with the right flags, you just have to modify the scriptmodule in $HOME/RetroPie-Setup/scriptmodules/emulators/retroarch.sh and look into the sources_retroarch function here. You can change the branch/tag used to build RetroArch - and my advice would be to comment out the following applyPatch lines since the RetroPie specific patches might not apply cleanly to the release you would be using.

After that you can either use the RetroPie-Setup script to re-install RetroArch from source or run from the command line

cd $HOME/RetroPie-Setup
sudo ./retropie_packages.sh retroarch

to build and install from source.
NOTE: the resulting installation could have some quirks w.r.t. RetroPie integration, but it would add the necessary dependencies for building RetroArch on Pi4 and the proper compile flags to make it work.

Alternatively, if you'd like to build manually, use the following CFLAGS when configuring RetroArch:

-O2 -march=armv8-a+crc -mtune=cortex-a72 -mfpu=neon-fp-armv8 -mfloat-abi=hard -ftree-vectorize -funsafe-math-optimizations

MrLightgun

Thank you @mitu

I was happy with V1.7.6 so I did this:

**cd
git clone https://github.com/libretro/RetroArch.git
cd RetroArch
git checkout tags/v1.7.6

CFLAGS="-O2 -march=armv8-a+crc -mtune=cortex-a53 -mfpu=neon-fp-armv8 -mfloat-abi=hard -ftree-vectorize -funsafe-math-optimizations" ./configure --disable-sdl --enable-sdl2 --disable-oss --disable-al --disable-jack --disable-qt --disable-x11 --disable-pulse --enable-neon --enable-floathard --enable-dispmanx

git apply ~/RetroPie-Setup/scriptmodules/emulators/retroarch/01_hotkey_hack.diff
git apply ~/RetroPie-Setup/scriptmodules/emulators/retroarch/02_disable_search.diff
git apply ~/RetroPie-Setup/scriptmodules/emulators/retroarch/03_disable_udev_sort.diff

I changed the source here

make
sudo cp retroarch /opt/retropie/emulators/retroarch/bin**

BUT I replaced the CFLAGS with what you provided but I didn't previously spot the ./configure part. Could you tell me the ./configure parameters for the Pi4 also please? Thank you so much for your help.

Mr Lightgun

mitu

The parameters to ./configure are dynamically created, but something like this should work:

/configure --prefix=/opt/retropie/emulators/retroarch --disable-sdl --enable-sdl2 --disable-oss --disable-al --disable-jack --disable-qt --disable-pulse --enable-opengles --disable-videocore --disable-vulkan --disable-wayland --enable-kms --enable-egl --enable-floathard --enable-neon

MrLightgun

Thank you @mitu

That worked, I needed to throw in a --disable-x11 too:

CFLAGS="-O2 -march=armv8-a+crc -mtune=cortex-a72 -mfpu=neon-fp-armv8 -mfloat-abi=hard -ftree-vectorize -funsafe-math-optimizations" ./configure --prefix=/opt/retropie/emulators/retroarch --disable-sdl --enable-sdl2 --disable-oss --disable-al --disable-jack --disable-qt --disable-pulse --enable-opengles --disable-videocore --disable-vulkan --disable-wayland --enable-kms --enable-egl --enable-floathard --enable-neon --disable-x11

I may have got rid of the --prefix bit, I can't quite remember now.

Appreciate the help.

Mr Lightgun