[colord] Are display device IDs still unique if EDID contains no 'ASCII' serial?

[Richard Hughes]

On 16 December 2011 23:37, Florian Höch <lists+colord at hoech.org> wrote:
> From what I've seen so far, the device IDs for displays in colord's database
> end with the ASCII serial from EDID, or as fallback with the serial number
> from bytes 12...15 if the former isn't set (if the EDID is available at
> all).

Yup, have a look at
https://gitorious.org/colord/master/blobs/master/doc/device-and-profile-naming-spec.txt
for all the juicy details.

> I looked at the raw EDID of my screens, all from different manufacturers,
> and they all have the same serial at bytes 12...15 (16843009, hex 01010101).
> Most of them except my Philips LCD TV have a unique non-generic monitor name
> and ASCII serial though.

Some EDID data really sucks.

> I'm wondering if, in the case that there is no ASCII serial available from
> EDID and the monitor name is very generic, could it be possible to introduce
> duplicate device ID entries in colord's database if several of these devices
> are connected?

Well, if you try to create a duplicate device, you get an error. If
there are two monitors attached with the same serial number then we
really just use the same profile for both of them, as to colord they
are the *same* device.

> 'xrandr_Philips_Consumer_Electronics_Company_Philips_FTV_16843009', so
> basically I'm wondering what's going to happen if I e.g. had another Philips
> TV connected (but I only have the one, so I can't try it).
> Has this been thought of?

Yes and no. There's really not a lot we can do, other than blacklist
EDIDs and fall back to the xrandr-{%xrandr_name} format.

Richard.