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

Stephen Warren swarren at nvidia.com
Wed May 18 01:14:41 CEST 2011

pl bossart wrote at Tuesday, May 17, 2011 4:12 PM:
> > Perhaps the vendor-specific data space could be useful for matching audio
> > ports to X displays; there is a 64-bit Port_ID in the ELD that might be
> > used for that, or we could define X/Linux/Unix as the vendor, and specify
> > the format of the vendor-specific data in a way that defines this mapping.
> Sounds complicated...The spec says this PortID field is "a ""canned""
> field that would be populated through implementation specific mean of
> default programming before the graphic driver is loaded". Duh?

I'm pretty sure our HW doesn't initialize this to anything meaningful before
the video driver runs.

> The standard "Monitor Name String" may be easier to use...

Do you mean co-opt this field and store alternate data in it? The real
monitor name for both monitors in my dual-head setup are the same...

> > That said, the internal APIs our graphics driver uses to write the ELD
> > is currently limited to 96 bytes (the size of the standardized section
> > of the ELD). I'm not sure yet if that's simply because 96 bytes was all
> > that was needed, or if that also ended up being encoded as a HW design
> > limitation.
> Looks like the max for ELDv2 is 80 bytes for the baseline+4 for the
> header.

Oh yeah; I'd calculated assuming SADs were 4 bytes but they're 3.


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