On Thu, Feb 16, 2017 at 09:24:09AM -0800, Manasi Navare wrote: > On Thu, Feb 16, 2017 at 07:18:57PM +0200, Ville Syrjälä wrote: > > On Thu, Feb 16, 2017 at 09:07:53AM -0800, Manasi Navare wrote: > > > On Thu, Feb 16, 2017 at 05:30:07PM +0200, ville.syrj...@linux.intel.com > > > wrote: > > > > From: Ville Syrjälä <ville.syrj...@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. > > > > > > > > Cc: sta...@vger.kernel.org > > > > Cc: Palmer Dabbelt <pal...@dabbelt.com> > > > > Reported-by: Palmer Dabbelt <pal...@dabbelt.com> > > > > References: > > > > https://lists.freedesktop.org/archives/intel-gfx/2017-February/119779.html > > > > Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com> > > > > --- > > > > drivers/gpu/drm/i915/intel_dp.c | 15 +++++++++++---- > > > > 1 file changed, 11 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/i915/intel_dp.c > > > > b/drivers/gpu/drm/i915/intel_dp.c > > > > index 024798a9c016..37a746f7fbc3 100644 > > > > --- a/drivers/gpu/drm/i915/intel_dp.c > > > > +++ b/drivers/gpu/drm/i915/intel_dp.c > > > > @@ -4648,11 +4648,18 @@ 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 was connected already and is still > > > > connected > > > > - * check links status, there has been known issues of > > > > - * link loss triggerring long pulse!!!! > > > > + * 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 > > > > apparely > > > > + * 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. > > > > */ > > > > drm_modeset_lock(&dev->mode_config.connection_mutex, > > > > NULL); > > > > intel_dp_check_link_status(intel_dp); > > > > -- > > > > > > So here we basically just ignore the connector status and retrain > > > irrespectively. > > > > We ignore the _previous_ connector status. > > > > > But that means even if we have newer values now for max link rate/lane > > > count from > > > DPCD, during this retrain we are just using the stale value of > > > intel_dp->link_rate > > > and intel_dp->lane_count. I think intel_dp->link_rate and lane count > > > values > > > should be set to 0 on HPD pulse, they would be set only during a modeset. > > > > The DPCD has already been parsed by this time. > > > > -- > > Ville Syrjälä > > Intel OTC > > Yes, we have parsed the DPCD but we dont write to intel_dp->link-rate and > intel_dp->lane_count > until we do a modeset (these get written during pre_enable) and these values > get used > during the retraining of the link. So at this point we will still use stale > values.
They're not stale. They're exactly what we used when we set up the mode that's still being drive out. This is just retraining the link at the same parameters. > Shouldnt we set the link status to BAD and send a hotplug event, like the > solution we implemneted > for retraining? > > Regards > Manasi > > Regards > Manasi -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
