Good news regarding tearing and low EmulationStation performance on Pi 4

George Spiggott

Purely as a guide to how it may run on some possible future 64bit Retropie/Dolphin build has anyone tried these new drivers on a Gentoo/dolphin (or similar) build?

saccublenda

I managed to update the kernel to 5.4.29, but when I launch ES with dtoverlay= vc4-kms-v3d I get these flashing artifacts

Brunnis

@saccublenda That looks really weird... What resolution are you running at?

saccublenda

@Brunnis 1920x1080

saccublenda

@Brunnis I guess it is an overscan problem. Removing the overscan settings from /boot/config.txt makes the artifacts disappear.

cellux

Video works fine using the kms driver, I don't have screen tearing anymore in some more problematic mame and n64 games.

However, sound is gone. When I try to change settings in raspi config i get "there was an error running a4 audio"

Is there some solution for this? In raspberry pi forum I've seen some audio related posts, tried to switch to the new kms hdmi audio driver (editing vc4-hdmi.conf), that results in no default audio driver found messages.

Brunnis

@cellux Sorry, can't help with that. I started with a fresh RetroPie weekly image, updated to the 5.4 kernel and enabled the full KMS driver and audio just worked.

cellux

@Brunnis With the old kernel running aplay -l i got card 0: ALSA [bcm2835 ALSA]

Using the new kernel this disappears and only get a card called vc4hdmi.. In theory alsa / bcm2835 sound card is enabled by dtparam=audio=on in the boot config, but that just doesn't seem to happen for me. It's a shame since video works so much better with the new one.

I did force hdmi with my old setup in es and also raspi-config.. wondering whether that could have saved some config that causes issues now. Will try to downgrade and reset as much as possible to default settings.

mitu

@cellux said in Good news regarding tearing and low EmulationStation performance on Pi 4:

Using the new kernel this disappears and only get a card called vc4hdmi.. In theory alsa / bcm2835 sound card is enabled by dtparam=audio=on in the boot config, but that just doesn't seem to happen for me. It's a shame since video works so much better with the new one.

You'll have to add the configurations specified in the RPI forums topic in order to get audio working. dtparam=audio=on doesn't apply to the configuration anymore.

cellux

@mitu

Can you point me to the post that has that configuration please? I've read the pi forum and gradually tried all relevant things I've found:

removing dt param audio
the new configuration in /usr/share/alsa/cards/vc4-hdmi.conf
adding alias vc4-hdmi1 cards.vc4-hdmi

mitu

@cellux I was referring to https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=269769&p=1636828#p1636828.

cellux

@mitu
Ah ok.. unfortunately that doesn't work at all for me (audio off, right kms dt overlay, etc) No sound and raspi-config throws up when I try access audio settings.

I got a nice tip though. It is possible to use the old sound driver:
dtparam=audio=on
dtoverlay=vc4-kms-v3d-pi4,audio=off
(and the old vc4-hdmi.conf)

cellux

@cellux After kernel update and switching to 64 bit, I get audio using the kms driver's audio.

Swampy

Some of my experiences with kernel 5.4 on the raspberry pi 4:

With dtoverlay=vc4-kms-v3d everything works, except the splashscreen. I think, that's because openMAX and omxplayer doesn't work with kms. The same problem with emulators, where dispmanx is enabled (dispmanx is not supported with kms). Steamlink doesn't work with kms too. The new kms-audiodriver is working fine for me.

With dtoverlay=vc4-fkms-v3d everything works. Emulationstation is working as fluently, as with the real kms driver.

saccublenda

@Swampy Does kodi work for you with dtoverlay=vc4-kms-v3d?

Swampy

@saccublenda Sorry, I don't use kodi within retropie. I have an extra sd card with libreelec installed.

Rascas

@saccublenda Nope. It starts but doesn't play videos because it uses MMAL.
Only Kodi 19 will work fine with KMS, which has support for v4l2 hardware decoding.

saccublenda

@Rascas Ok, thanks for the info.

George Spiggott

Was this added to the weekly update (4.5.19) because all my screen tearing symptoms seem to have gone?

pbohannon

@saccublenda said in Good news regarding tearing and low EmulationStation performance on Pi 4:

@Brunnis I guess it is an overscan problem. Removing the overscan settings from /boot/config.txt makes the artifacts disappear.

Hi there! I'm having the exact visual artifact you posted in the your initial reply to the thread. However, I have no overscan options set in my config.txt. The only active settings I have are:

dtparam=audio=on

[pi4]
dtoverlay=vc4-kms-v3d
dtoverlay=rpivid-v4l2
max_framebuffers=2
arm_freq=2100
gpu_freq=700
over_voltage=6
hdmi_force_hotplug=1
gpi_mem=320

Do you, or anyone else monitoring, have any ideas as to where the described artifact comes from and how to prevent it? Am using 5.4.44-vl7l+ on a rpi4b 4GB. Kodi is installed, using ffmpeg 4.2.2, and I have made no changes to Mesa. Any ideas would be very much appreciated! Thanks very much.