[alsa-devel] [PATCH] ALSA: HDA: Add jack detection for HDMI

pl bossart bossart.nospam at gmail.com
Tue May 17 22:51:13 CEST 2011

>> >> a) Is it possible to report more information alongside the plug events,
>> >> such as ELD/EDID content? Or, is the idea that the kernel sends a plug
>> >> event, and then user-space retrieves that information via some other
>> >> API? I don't think there's an API to retrieve ELD information at present
>> >> though right? Although certainly it'd make sense for that to be a
>> >> completely separate patch.
>> >
>> > A simple approach would be adding a control element containing
>> > byte-array of ELD/EDID.
>> Are there any examples of such controls? Or are we talking about a new
>> kind of control?
> Look for SNDRV_CTL_ELEM_TYPE_BYTES.  Some codecs provide these.

Thanks for the pointer. looks simple enough to expose the ELD bytes.
This type of element can store up to 512 bytes, enough to store the
ELD header+baseline fields (260 bytes tops). I don't think userspace
would want to muck with vendor-specific information?
we may need an array of ELD controls in case there are several
monitors. Not sure how to represent which one is actually used. The
ELD is linked to a specific nid (node id), we'd need to link this to
the audio device #?

More information about the Alsa-devel mailing list