Sound issues with Dell Latitude 7490 (kabylake)

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: