[PATCH] drm: document that user-space should avoid parsing EDIDs

[Daniel Stone]

Hi,

On Fri, 9 Oct 2020 at 10:24, Simon Ser <contact at emersion.fr> wrote:
> User-space should avoid parsing EDIDs for metadata already exposed via
> other KMS interfaces and properties. For instance, user-space should not
> try to extract a list of modes from the EDID: the kernel might mutate
> the mode list (because of link capabilities or quirks for instance).
>
> Other metadata not exposed by KMS can be parsed by user-space. This
> includes for instance monitor identification (make/model/serial) and
> supported color-spaces.

So I take it the only way to get modes is through the connector's list
of modes. That sounds reasonable enough to me, but I think to properly
handle colour (e.g. CEA modes have different behaviour for
limited/full range depending on which VIC they correspond to IIRC)
we'd need to take more bits out of drm_mode_modeinfo::flags, which is
unfortunate since there aren't that many of them left and it's not an
extensible structure. Maybe proper mode handling is going to require
an expanded mode structure, but today is not that day, so:
Acked-by: Daniel Stone <daniels at collabora.com>

Cheers,
Daniel