Re: Sound issues with Dell Latitude 7490 (kabylake)

On 10/1/18 5:57 PM, Johannes Lundberg wrote:
> Hi
>
> While sound work out of the box (with headphone switching) on the 1-2 year
> older Latitude 7270, it does not on my new machine.
>
> The internal speaker works fine. If I plug in external speakers in the
> headphone jack, sound still goes to the internal speaker while a very load
> buzz comes from the external speakers.
>
> Do we have a solution for this?
>
> # cat /dev/sndstat
> Installed devices:
> pcm0: <Realtek ALC256 (Internal Analog)> (play/rec) default
> pcm1: <Realtek ALC256 (Front Analog Headphones)> (play)
> pcm2: <Intel Kabylake (HDMI/DP 8ch)> (play)
> No devices installed from userspace.
>
> # sysctl hw.snd
> hw.snd.maxautovchans: 16
> hw.snd.default_unit: 0
> hw.snd.version: 2009061500/amd64
> hw.snd.default_auto: 1
> hw.snd.verbose: 0
> hw.snd.vpc_mixer_bypass: 1
> hw.snd.feeder_rate_quality: 1
> hw.snd.feeder_rate_round: 25
> hw.snd.feeder_rate_max: 2016000
> hw.snd.feeder_rate_min: 1
> hw.snd.feeder_rate_polyphase_max: 183040
> hw.snd.feeder_rate_presets: 100:8:0.85 100:36:0.92 100:164:0.97
> hw.snd.feeder_eq_exact_rate: 0
> hw.snd.feeder_eq_presets:
> PEQ:16000,0.2500,62,0.2500:-9,9,1.0:44100,48000,88200,96000,176400,192000
> hw.snd.basename_clone: 1
> hw.snd.compat_linux_mmap: 0
> hw.snd.syncdelay: -1
> hw.snd.usefrags: 0
> hw.snd.vpc_reset: 0
> hw.snd.vpc_0db: 45
> hw.snd.vpc_autoreset: 1
> hw.snd.timeout: 5
> hw.snd.latency_profile: 1
> hw.snd.latency: 5
> hw.snd.report_soft_matrix: 1
> hw.snd.report_soft_formats: 1
>
> # sysctl dev.pcm
> dev.pcm.2.bitperfect: 0
> dev.pcm.2.buffersize: 65536
> dev.pcm.2.play.vchanformat: s16le:2.0
> dev.pcm.2.play.vchanrate: 48000
> dev.pcm.2.play.vchanmode: passthrough
> dev.pcm.2.play.vchans: 1
> dev.pcm.2.play.32bit: 24
> dev.pcm.2.%parent: hdaa1
> dev.pcm.2.%pnpinfo:
> dev.pcm.2.%location: nid=3
> dev.pcm.2.%driver: pcm
> dev.pcm.2.%desc: Intel Kabylake (HDMI/DP 8ch)
> dev.pcm.1.bitperfect: 0
> dev.pcm.1.buffersize: 65536
> dev.pcm.1.play.vchanformat: s16le:2.0
> dev.pcm.1.play.vchanrate: 48000
> dev.pcm.1.play.vchanmode: fixed
> dev.pcm.1.play.vchans: 1
> dev.pcm.1.play.32bit: 24
> dev.pcm.1.%parent: hdaa0
> dev.pcm.1.%pnpinfo:
> dev.pcm.1.%location: nid=33
> dev.pcm.1.%driver: pcm
> dev.pcm.1.%desc: Realtek ALC256 (Front Analog Headphones)
> dev.pcm.0.bitperfect: 0
> dev.pcm.0.buffersize: 65536
> dev.pcm.0.rec.vchanformat: s16le:2.0
> dev.pcm.0.rec.vchanrate: 48000
> dev.pcm.0.rec.vchanmode: fixed
> dev.pcm.0.rec.vchans: 1
> dev.pcm.0.rec.autosrc: 2
> dev.pcm.0.rec.32bit: 24
> dev.pcm.0.play.vchanformat: s16le:2.0
> dev.pcm.0.play.vchanrate: 48000
> dev.pcm.0.play.vchanmode: fixed
> dev.pcm.0.play.vchans: 2
> dev.pcm.0.play.32bit: 24
> dev.pcm.0.%parent: hdaa0
> dev.pcm.0.%pnpinfo:
> dev.pcm.0.%location: nid=20,18
> dev.pcm.0.%driver: pcm
> dev.pcm.0.%desc: Realtek ALC256 (Internal Analog)
> dev.pcm.%parent:


You could try

sysctl dev.hdaa.0.nid33_config="as=1 seq=15 device=Headphones"

sysctl dev.hdaa.0.reconfig=1


It should result in you having only one pcm device for the two outputs 
and it should switch from

internal to external when you plug in the external speakers and vice versa.

To make it permanent put 'hint.hdaa.0.nid33.config="as=1 seq=15 
device=Headphones"' in your loader.conf


The loud buzz is a bit worrying, it could be related to the problem I 
have been having, where I got strange sound

when using headphones on my laptop. I have worked around it by patching 
the sound driver, I have kept my local

patch for years.


Jakob