Howto : optimized /boot/config.txt

bilu

Below my simplified /boot/config.txt (Rpi4 4GB, HW version 1.1), followed by explanations.

disable_splash=1
disable_overscan=1
hdmi_group=1
hdmi_mode=4
hdmi_drive=2
hdmi_ignore_cec_init=1
arm_freq=2048
v3d_freq=750
over_voltage=6
dtparam=i2c_arm=on
dtparam=audio=on
enable_uart=1
[pi4]
dtoverlay=vc4-fkms-v3d
[all]
hdmi_enable_4kp60=1

Hardware revision?
www.raspberrypi.org/documentation/hardware/raspberrypi/revision-codes/README.md
www.cnx-software.com/2020/02/24/raspberry-pi-4-rev-1-2-fixes-usb-c-power-issues-improves-sd-card-resilience/

Seems my RPi4 version is more sensitive to what chargers I can use, therefore limits overclocking options.

cat /proc/cpuinfo | grep Revision
Revision : c03111

Overclocking
Reference: www.raspberrypi.org/documentation/configuration/config-txt/overclocking.md

These are the speeds I achieve with arm_freq=2048. arm_freq=2047 reports a lower scaling_max_freq which can be noticed in games like God of War: Chains of Olympus (one of the games I used as benchmark). v3d_freq=750 is the max GPU overclock, over_voltage=6 required to provide extra juice (over_voltage=5 worked for me with arm_freq=2000).

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
2194967

echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
vcgencmd measure_clock arm
frequency(48)=2048519552

As for hdmi_enable_4kp60=1 I also use it for overclocking reasons, as the only way to increase the GPU core_freq from 500 to 550, enable_tvout underclocks to 360:
"Specific to Pi 4B: The core_freq of the Raspberry Pi 4 can change from the default if either hdmi_enable_4kp60 or enable_tvout are used, due to relationship between internal clocks and the particular requirements of the requested display modes."

HDMI options and resolution
Reference: www.raspberrypi.org/documentation/configuration/config-txt/video.md

hdmi_group=1, hdmi_mode=4, hdmi_drive=2 : these options set the RPi at 16:9 720p using the standard CEA TV timings and sending audio through HDMI.

hdmi_ignore_cec_init=1 "prevents a CEC-enabled TV from coming out of standby and channel-switching when you are rebooting your Raspberry Pi."
Channel switching on reboots was quite annoying indeed :)

No gpu_mem parameters??
Reference: www.raspberrypi.org/documentation/configuration/config-txt/memory.md

That's right! :) "On the Raspberry Pi 4 the 3D component of the GPU has its own memory management unit (MMU), and does not use memory from the gpu_mem allocation. Instead memory is allocated dynamically within Linux. This may allow a smaller value to be specified for gpu_mem on the Pi 4, compared to previous models."

The performance of N64 Conker's Bad Fur Day increased noticeably after removing all gpu_mem parameters.

bilu

My other relevant threads
https://retropie.org.uk/forum/topic/27429/howto-emulator-performance-tweaks-for-psp-and-n64-and-quality-for-psx
https://retropie.org.uk/forum/topic/27431/howto-major-performance-boost-on-retroarch-based-emulators
https://retropie.org.uk/forum/topic/27428/howto-change-output-resolution-to-720p-on-libretro-retroarch-emulators

mitu

@bilu The gpu_mem parameters are still needed for the GPU's video decoders (MP4/MP5). Without it set up to at least 256M, you'll get issues when playing videos.

Regarding the other settings

RetroPie allows you to switch to the performance governor through the Runcommand settings, so you don't need to manually do that.
hdmi_drive is ignored on the PI4

downerhouse

@bilu just to say thanks. To date, I've been underwhelmed by the PI4 performance since I swapped from my pi3.

I've been struggling with all kinds of screen tearing issues, despite overclocking to 2.1ghz.

I borrowed this configuration and everything is now running buttery smooth.

Thanks for sharing.