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#1 2017-05-21 00:57:21

nabilh2020
Banned
Registered: 2017-05-21
Posts: 6

Sound over HDMI for LPE

Will Kernel 4.12 finally solve the audio for i915 LPE devices.

I tried to modify the .config and sound>x86>Kfonfig to get sound
in both 4.11 & 4.12 with no success,

whereas this is resolved in Ubuntu since 4.11.

actual module gets built as  /lib/modules/4.12.0-rc1-g2b6b38b04c2e+/kernel/sound/x86/snd-hdmi-lpe-audio.ko.gz
but still no sound.

I know there is a series of patches for this but it's for Kernel 4.7 I think.

Last edited by nabilh2020 (2017-05-21 01:13:43)

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#2 2017-05-21 23:20:24

nabilh2020
Banned
Registered: 2017-05-21
Posts: 6

Re: Sound over HDMI for LPE

linux-mainline RC1-1 seems to have solved the problem for Intel Cherrytrail LPE sound.

Q; On its own with change in kernel userspace, or with mods I made to .config
& Kconfig in sound/x86

.config LPE entries added -

#
# CODEC drivers
#
...
CONFIG_SND_X86=y
CONFIG_HDMI_LPE_AUDIO=m
...

Kconfig in sound/x86
modded to

menuconfig SND_X86
    bool "X86 sound devices"
    depends on X86
    default y
    ---help---
      X86 sound devices that don't fall under SoC or PCI categories

if SND_X86

config HDMI_LPE_AUDIO
    tristate "HDMI audio without HDaudio on Intel Atom platforms"
    depends on DRM_I915
    default y
    select SND_PCM
    help
     Choose this option to support HDMI LPE Audio mode

endif    # SND_X86

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#3 2017-05-22 00:24:38

loqs
Member
Registered: 2014-03-06
Posts: 17,192

Re: Sound over HDMI for LPE

linux-mainline 4.12rc1-1 already had those config options set see https://aur.archlinux.org/cgit/aur.git/ … 7a5a#n5612 and https://aur.archlinux.org/cgit/aur.git/ … 7a5a#n5613
Did adding default y to the config HDMI_LPE_AUDIO stanza of src/linux-4.11/sound/x86/Kconfig cause the module to be built in or did the config preserve it as a separate module?

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#4 2017-05-23 05:45:57

nabilh2020
Banned
Registered: 2017-05-21
Posts: 6

Re: Sound over HDMI for LPE

loqs wrote:

linux-mainline 4.12rc1-1 already had those config options set see https://aur.archlinux.org/cgit/aur.git/ … 7a5a#n5612 and https://aur.archlinux.org/cgit/aur.git/ … 7a5a#n5613
Did adding default y to the config HDMI_LPE_AUDIO stanza of src/linux-4.11/sound/x86/Kconfig cause the module to be built in or did the config preserve it as a separate module?

For 4.11 & 4.12-RC1-0 - I checked and had to set both .config & x86 Kconfig manually.

This still didn't give audio but dummy output.

Then I built mainline, and changed manually Kconfig, but can't recall if I changed .config, though I think I did.
with linux-mainline sound then got set up correctly.

I also checked with baytrail, and sound works too.

However I did a pacman -Syu, & there were a few alsa files upgraded, I guess this might have part of the trick.

With baytrail with linux-mainlne (which is now RC1-1) there is still the Wifi & BT on baytrail to sort out.
Trying yaourt 8723bs either as extra module or DKMS leads to errors.
It is built in linux-baytrail411 (RC$), but then no sound.

The latest 4.11 has built the LPE driver (again I made .config & Kconfig change, also benefiting of the userspace upgrade) so will need to check if it solves sound too.

For cherrytrail with linux mainline (4.12 RC1-1) all drivers are working, so I might operate from this when I use Arch Linux.

For baytrail with linux-mainline, no WiFi, no BT so need usb dongles, or use linux-baytrail411 & use an audio usb & a BT dongle. Baytrail is far from fully covered.

Last edited by nabilh2020 (2017-05-23 06:00:08)

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#5 2017-05-26 02:22:46

nabilh2020
Banned
Registered: 2017-05-21
Posts: 6

Re: Sound over HDMI for LPE

The last Kernel release 4.11.2-1 solved all issues on HDMI Baytrail stick bar Bluetooth, which requires special treatment as I learnt with and applied to Ubuntu, same trick doesn't work for Arch linux.

Kernel 4.12 cannot currently solve RTL8723BS WiFi as 4.11-1 & above do, not a problem for Cherrytrail as an Intel WiFi driver is used.

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