[alsa-devel] No audio on headphones on HP X2 210 (Baytrail Atom - RT5640)

[Pierre-Louis Bossart]

On 4/4/18 3:39 AM, Freaky wrote:
> Hi there,
> 
> we're running Fedora 27 on a HP X2 210. Grabbed the UCM config files for it
> from the GIT repo of plbossart (
> https://github.com/plbossart/UCM/tree/master/bytcr-rt5640) blacklisted the
> snd_hdmi_lpe_audio and sound now works via the onboard speakers.
> 
> Current kernel is 4.15.13.
> 
> Audio via the headphones does not work. Been looking at the source code,
> but most of the abbreviations are mumbo jumbo to me :). Doesn't look like
> there are any for the headphones in 4.15.13.

Define 'work'...
The headset support for the RT5640 has been there for a while, but you 
need to manually select the output.

> 
> Did find this patch:
> https://webcache.googleusercontent.com/search?q=cache:FlvUx7XgbH4J:https://github.com/jwrdegoede/linux-sunxi/commit/+&cd=3&hl=en&ct=clnk&gl=nl
> 
> Which seems to enable a quirk for headphone detection. Doesn't seem to be
> in 4.15.14 source. Do we require that patch? Not sure what this line does:

that is jack detection, which is different. It enables automatic 
switching to the headset on insertion, but you still need to verify if 
the headsets work in the first place.

> 
> #define BYT_RT5640_JACK_PIN(quirk) ((quirk) & GENMASK(15, 13))
> 
> Would I need to flip bits 15 and 13? What would the parameter be? The file
> is called bytcr_rt5640.c, but for the 5645 (Cherrytrail atoms) the kernel
> parameter is called snd_soc_rt5645.quirk, is it called snd_soc_rt5640.quirk
> here? Doubt it since there are quirks defined in sound/soc/codecs/rt5645.c
> whereas I don't see any (4.15.14 sources) in sound/soc/codecs/rt5640.c.
> 
> Any advise would be most welcome :).
> 
> Thanks in advance.
> 
> Kind regards,
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