On Fri, 08 Jan 2016 11:46:23 +0100, Russell King - ARM Linux wrote:
Given that, I'd like to throw in here another detail: iirc, i915's HDMI exports the ELD to userspace via a control called "ELD" - see eld_bytes_ctl in sound/pci/hda/patch_hdmi.c. This allows userspace to monitor, and read the ELD including which compressed audio formats are supported. I'm not currently aware of anything that makes use of this, but as there is this precedent for exporting this information, maybe it should become a standard way, so that video playback applications can then select an appropriate audio stream depending on the current properties of the connected device?
Right, the ELD ctl elements were introduced exactly for such a purpose. Though, I'm not sure currently which user-space app is actually referring to this information, too. But certainly it's a good thing to have for other drivers.
Takashi