| Message ID | 20170412193017.21029-1-ville.syrjala@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Apr 12, 2017 at 10:30:17PM +0300, ville.syrjala@linux.intel.com wrote: > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > Apparently some DP sinks are a little nuts and cause HPD to drop > intermittently during modesets. This happens eg. on an ASUS PB287Q. > In oder to recover from this we can't really use the previous > connector status to determine if the link needs retraining, so let's > just ignore that piece of information and do the retrain > unconditionally. We do of course still check whether the link is > supposed to be running or not. > > To actually get read out the EDID and update things properly we > also need to nuke the goto out added by commit 7d23e3c37bb3 > ("drm/i915: Cleaning up intel_dp_hpd_pulse"). I'm actually not sure > why that was there. Perhaps to avoid an EDID read if the connector > status didn't appear to change, but that sort of thing is quite racy > and would have failed anyway if we failed to keep up with the > hotplugs (if we missed the HPD down in between two HPD ups). And > now that we take this codepath unconditionally we definitely need > to drop the goto as otherwise we would never do the EDID read. > > v2: Drop the goto that made us skip EDID reads entirely. Doh! > v3: Rebase due to locking changes > s/apparely/apparently/ in the comment (Chris) > > Cc: stable@vger.kernel.org > Cc: Manasi Navare <manasi.d.navare@intel.com> > Cc: Palmer Dabbelt <palmer@dabbelt.com> > Reported-by: Palmer Dabbelt <palmer@dabbelt.com> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99766 > References: https://lists.freedesktop.org/archives/intel-gfx/2017-February/119779.html > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> And pushed to dinq. Thanks for the review. > --- > drivers/gpu/drm/i915/intel_dp.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index 16b7bf7af537..09601a22d3cc 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -4685,9 +4685,20 @@ intel_dp_long_pulse(struct intel_connector *intel_connector) > */ > status = connector_status_disconnected; > goto out; > - } else if (connector->status == connector_status_connected) { > + } else { > + /* > + * If display is now connected check links status, > + * there has been known issues of link loss triggerring > + * long pulse. > + * > + * Some sinks (eg. ASUS PB287Q) seem to perform some > + * weird HPD ping pong during modesets. So we can apparently > + * end up with HPD going low during a modeset, and then > + * going back up soon after. And once that happens we must > + * retrain the link to get a picture. That's in case no > + * userspace component reacted to intermittent HPD dip. > + */ > intel_dp_check_link_status(intel_dp); > - goto out; > } > > /* > -- > 2.10.2
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 16b7bf7af537..09601a22d3cc 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4685,9 +4685,20 @@ intel_dp_long_pulse(struct intel_connector *intel_connector) */ status = connector_status_disconnected; goto out; - } else if (connector->status == connector_status_connected) { + } else { + /* + * If display is now connected check links status, + * there has been known issues of link loss triggerring + * long pulse. + * + * Some sinks (eg. ASUS PB287Q) seem to perform some + * weird HPD ping pong during modesets. So we can apparently + * end up with HPD going low during a modeset, and then + * going back up soon after. And once that happens we must + * retrain the link to get a picture. That's in case no + * userspace component reacted to intermittent HPD dip. + */ intel_dp_check_link_status(intel_dp); - goto out; } /*