Display Rotate with Rpi3 and current RetroPie Image [solved]

[Lolonois]

What options exist to rotate the framebuffer in RetroPie by 180 degrees in 2024? I have a setup where a desktop TFT is mounted upside-down.

Details:
Rpi3 3b+ with latest RetroPie Image
Updated packages and latest RetroPie-Setup (94b131a6)
Monitor connected via HDMI
Kernel: Linux retropie 5.10.103-v7+ #1529 SMP Tue Mar 8 12:21:37 GMT 2022 armv7l GNU/Linux

I tried to add video=HDMI:<xres>x<yres>@60,rotate=180 to /boot/cmdline.txt, as suggested on the Raspberry page, but it does not make a difference. (However, this extra option works well on a Rpi4).

If all else fails I go back to a firmware/kernel combo where display_rotate=2 in /boot/config.txt is still supported and apt mark/hold this combo. Another workaround I see is to use the rotation option for ES and for the libretro/RA based emulators. However, for non libretro emulators this still might be a hit/miss situation.

[Lolonois]

Found it. I was misled by the official Rpi documentation.

The solutions below only refer to the display rotation, see notes.

Solution 1: Legacy video driver

• config.txt: Neither dtoverlay=vc4-fkms-v3d nor dtoverlay=vc4-kms-v3d enabled, but display_hdmi_rotate=2
• cmdline.txt: No video=... option

Note: The RetroPie Image for a Rpi3 ships with the legacy driver enabled. The EmulationStation binary is compiled against that driver and works out-of-the-box. This should also not affect any precompiled emulators.

Solution 2: (fake) KMS and Kernel option

• config.txt: Either dtoverlay=vc4-fkms-v3d or dtoverlay=vc4-kms-v3d
• cmdline.txt: Add video=HDMI-A-1:1280x1024@60,rotate=180. Note the use of HDMI-A-1 and not HDMI as the documentation (see above) states currently. (I have a PR filed for that.)

Note: You will have to source build emulationstation with that config to make it use the video driver. I did not testdrive any emulators with this solution.