[Intel-gfx] [PATCH] drm: Silence zero EDID carping

[Ville Syrjälä]

On Thu, Oct 29, 2020 at 04:01:23PM +0000, Chris Wilson wrote:
> Quoting Ville Syrjälä (2020-10-29 14:07:46)
> > On Thu, Oct 29, 2020 at 11:00:30AM +0000, Chris Wilson wrote:
> > > We have a few displays in CI that always report their EDID as a bunch of
> > > zeroes. This is consistent behavioud, so one assumes intentional
> > > indication of an "absent" EDID. Let us treat is as such by silently
> > > reporting the zero edid using connector->null_edid_counter, leaving the
> > > loud carp to EDID that violate their checksums or otherwise return
> > > unexpected illegal data upon reading. These are more likely to be
> > > inconsistent bad connections rather than being intended.
> > 
> > I don't think null_edid_counter is actually used by anything.
> > So apart from wondering why the mode list has turned strange
> > is there some way I can still see from the logs that the
> > EDID has become all zeroes?
> 
> The ones in question, it's every time we read the EDID it comes back
> zero. I am betting that transient everything-is-zero rather than
> spurious data is rare enough not to worry about.
> 
> An alternative would be to pass the log level to the bad_edid dumper, or
> just make it debug for even gibberish edids?

I suspect debug should be good enough for this. The user is probably
going to notice some problem with their display resolution if the
EDID is bad/zero, so we should still get the bug report.

-- 
Ville Syrjälä
Intel