Bug#978025: Sound issues with the 5.10.x kernel (alsa)
Hi all, From: Stefan Wahren Subject: Re: Sound issues with the 5.10.x kernel (alsa) Date: Mon, 8 Feb 2021 13:22:56 +0100 >> This is basically me forwarding the bug I reported on Debian's BTS: >> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=978025 >> TL;DR: I have a RPi 3B+ running pure Debian Bullseye arm64 (~from >> raspi.debian.net), named rpi-mpd, connected via HDMI cable to my AV Receiver. > can you please confirm that the bcm2835-audio driver causing the issues? I think the root cause of this issue is that both vc4.ko and snd_bcm2835.ko try to provide ALSA sinks to HDMI audio outputs from RPi. Why do the two drivers provide the same functionality for the same device? It seems nonsense. There must be some coordination between vc4.ko and snd_bcm2835.ko on who provides ALSA sinks of RPi HDMI output. The non-coordination that both drivers provide different ALSA sinks of the same device already causes another symptom as http://lists.infradead.org/pipermail/linux-rpi-kernel/2021-March/008077.html Best regards, Ryutaroh Matsumoto
Bug#978025: Sound issues with the 5.10.x kernel (alsa)
> I think the root cause of this issue is that both vc4.ko and snd_bcm2835.ko > try to provide ALSA sinks to HDMI audio outputs from RPi. > Why do the two drivers provide the same functionality for the same device? > It seems nonsense. > There must be some coordination between vc4.ko and snd_bcm2835.ko > on who provides ALSA sinks of RPi HDMI output. Giving "enable_hdmi=0" to snd_bcm2835.ko does not improve the situation, while module_blacklisting snd_bcm2835 suppresses all the symptoms reported. snd_bcm2835.ko in 5.10.24 seems having a bug ignoring "enable_hdmi=0". Best regards, Ryutaroh
Bug#978025: Sound issues with the 5.10.x kernel (alsa)
Hi, Am 28.03.21 um 07:58 schrieb Ryutaroh Matsumoto: >> I think the root cause of this issue is that both vc4.ko and snd_bcm2835.ko >> try to provide ALSA sinks to HDMI audio outputs from RPi. >> Why do the two drivers provide the same functionality for the same device? >> It seems nonsense. >> There must be some coordination between vc4.ko and snd_bcm2835.ko >> on who provides ALSA sinks of RPi HDMI output. > Giving "enable_hdmi=0" to snd_bcm2835.ko does not improve the situation, > while module_blacklisting snd_bcm2835 suppresses all the symptoms reported. > snd_bcm2835.ko in 5.10.24 seems having a bug ignoring "enable_hdmi=0". i assume you set this option in the config.txt? This shouldn't have any affect for the mainline kernel / DT. > > Best regards, Ryutaroh
Bug#978025: Sound issues with the 5.10.x kernel (alsa)
>> i assume you set this option in the config.txt? This shouldn't have any >> affect for the mainline kernel / DT. > I am aware of that... I include my config.txt on RPi4B for reference... arm_64bit=1 enable_uart=1 upstream_kernel=1 kernel=vmlinuz-5.10.0-5-rt-arm64 initramfs initrd.img-5.10.0-5-rt-arm64 disable_fw_kms_setup=1 disable_overscan=1 hdmi_enable_4kp60=1 Best regards, Ryutaroh Matsumoto
