I have been with the Rpi people for 2 days working on this sound issue that really has been going on for 2 months with the newer kernels and now has crept into 5.10. Today they pushed the fix.
https://github.com/raspberrypi/linux/issues/4634
Long story short I have pushed a new 5.10 kernel with the fix to all branches when the mirrors sync.
This new kernel will install a new cmdline.txt and back up the old one so if someone has some custom configs in it they can refer to the backup and add back to the new cmdline.txt as long as snd-bcm2835.enable_compat_alsa=whatever & snd_bcm2835.enable_headphones=1 is not added back.
I hate to mess with someone’s custom config’s but I am trying to avoid another firestorm over this yet again needed config changes and be compatible with the new images that were released yesterday because some do not like to search/read the forum before they post an issue.
With this new kernel you will do like before to switch back and forth between fkms/kms in config.txt and do not have to mess with cmdline.txt at all.
The sound cards look better now also.
FKMS:
**** List of PLAYBACK Hardware Devices ****
card 0: b1 [bcm2835 HDMI 1], device 0: bcm2835 HDMI 1 [bcm2835 HDMI 1]
Subdevices: 4/4
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
card 1: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
Subdevices: 4/4
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
KMS:
**** List of PLAYBACK Hardware Devices ****
card 0: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 1: vc4hdmi0 [vc4-hdmi-0], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: vc4hdmi1 [vc4-hdmi-1], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
Packages Removed