tst87
Posts: 2
Joined: Sat Jan 11, 2020 2:30 pm

RPi 4 FKMS AV Receiver kills HDMI when changeing volume

Sat Jan 11, 2020 2:52 pm

Hi all,

I've connected my Raspberry Pi 4 via HDMI to a Sony STR-DH750 AV Receiver. The Pi runs Raspbian Buster Lite with Kodi.
This works fine, except for one annoying problem:

Everytime I change the volume of the receiver with the remote, the Pi seems to kill the HDMI connection for a couple of seconds and the current volume shows up on a black screen. Normally it's supposed to show up as an overlay on the Pi screen.

This happens only with the fake KMS driver enabled. If it's disabled it works as expected, but then Kodi stops working.

I'm using the original Pi HDMI cable and have already tried different options like forcing hdmi, ignoring edid, etc...

Thanks in advance for any ideas.

Regards,
Tobias

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dividuum
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Location: Germany
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Re: RPi 4 FKMS AV Receiver kills HDMI when changeing volume

Sat Jan 11, 2020 10:57 pm

tst87 wrote:
Sat Jan 11, 2020 2:52 pm
Everytime I change the volume of the receiver with the remote, the Pi seems to kill the HDMI connection for a couple of seconds and the current volume shows up on a black screen. Normally it's supposed to show up as an overlay on the Pi screen.
My guess would be that the overlay overloads the hardware video scaler (HVS) on the Pi. The HVS the hardware part the composes the final HDMI output from potentially multiple sources like a video or overlays. If the HVS is too slow generating a HDMI signal, this usually results in a briefly lost video signal. Maybe your receiver is more sensitive to that. The higher the resolution of your output, the more likely it is that additional layers trigger this effect. Do you use 4K by any chance?
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tst87
Posts: 2
Joined: Sat Jan 11, 2020 2:30 pm

Re: RPi 4 FKMS AV Receiver kills HDMI when changeing volume

Sun Jan 12, 2020 7:20 pm

Thanks for your answer. It makes sense to me. The receiver supports 4K but the TV does not. Even with 4K enabled on the Pi 4K does not show up with as supported mode.

I've tried different modes with lower resolutions and hvs_priority=0x32ff without luck. I'm still wondering why it works fine with the legacy driver.

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