Notes on E-EDID and DisplayID support

Adam Jackson ajax at
Thu Sep 18 11:16:28 PDT 2008

On Wed, 2008-09-17 at 13:48 -0400, Adam Jackson wrote:

> This will also get more complicated in the future.  Apparently
> constructing a conformant (hah!) EDID block was just too much work for
> some vendors, so there's a new spec called DisplayID from VESA that
> we'll have to deal with at some point.  From what I've been able to
> glean from the internet, it's a variable length format right from the
> start, which means we probably won't be able to convert it to
> cooked-EDID internally.  I'd know more, but I don't have the spec yet,
> as I don't have the site access password for VESA.  I think Egbert does
> though.
> For DisplayID I think we'd be better off with a new query API that keeps
> the internal representation away from the drivers.

I have the DID docs now!  It looks very much like the CEA EDID
extension, which really only reinforces my view that this needs to be
API and not pile-of-structs.

I think there's a straightforward way to programmatically detect
DisplayID blocks as opposed to EDID, so I'll probably add at least
hexdump for it to the DDC code.

- ajax
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