| Message ID | 20201029110030.9959-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm: Silence zero EDID carping | expand |
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? > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > --- > drivers/gpu/drm/drm_edid.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index 631125b46e04..94549805a204 100644 > --- a/drivers/gpu/drm/drm_edid.c > +++ b/drivers/gpu/drm/drm_edid.c > @@ -1951,7 +1951,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector, > break; > if (i == 0 && drm_edid_is_zero(edid, EDID_LENGTH)) { > connector->null_edid_counter++; > - goto carp; > + goto out; > } > } > if (i == 4) > -- > 2.20.1 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
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? -Chris
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.
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 631125b46e04..94549805a204 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -1951,7 +1951,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector, break; if (i == 0 && drm_edid_is_zero(edid, EDID_LENGTH)) { connector->null_edid_counter++; - goto carp; + goto out; } } if (i == 4)
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. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> --- drivers/gpu/drm/drm_edid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)