| Message ID | 20180918072009.4836-1-dhinakaran.pandiyan@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] drm/i915/dp: Fix link retraining comment in intel_dp_long_pulse() | expand |
On Tue, Sep 18, 2018 at 12:20:05AM -0700, Dhinakaran Pandiyan wrote: > Comment claims link needs to be retrained because the connected sink raised > a long pulse to indicate link loss. If the sink did so, > intel_dp_hotplug() would have handled link retraining. Looking at the > logs in Bugzilla referenced in commit '3cf71bc9904d ("drm/i915: Re-apply > Perform link quality check, unconditionally during long pulse"")', the > issue is that the sink does not trigger an interrupt. We want the > ->detect() from user space to check link status and retrain. Ville's > review for the original patch also indicates the same root cause. > > I have also renamed long_pulse() to full_detect(). have you?! I just see the comment change on this patch ;) > v2: Patch split and rewrote comment.. > > Cc: Lyude Paul <lyude@redhat.com> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > Cc: Jani Nikula <jani.nikula@linux.intel.com> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> > Cc: Jan-Marek Glogowski <glogow@fbihome.de> > References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse"") > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> > --- > drivers/gpu/drm/i915/intel_dp.c | 12 ++---------- > 1 file changed, 2 insertions(+), 10 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index 436c22de33b6..cac1c7c6cbfd 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -5074,16 +5074,8 @@ intel_dp_long_pulse(struct intel_connector *connector, > goto out; > } else { > /* > - * If display is now connected check links status, > - * there has been known issues of link loss triggering > - * 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. > + * Some monitors do not signal loss of link synchronization > + * with an IRQ_HPD, so force a link status check. > */ > struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base; > > -- > 2.14.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Tue, 2018-09-18 at 08:51 -0700, Rodrigo Vivi wrote: > On Tue, Sep 18, 2018 at 12:20:05AM -0700, Dhinakaran Pandiyan wrote: > > Comment claims link needs to be retrained because the connected > > sink raised > > a long pulse to indicate link loss. If the sink did so, > > intel_dp_hotplug() would have handled link retraining. Looking at > > the > > logs in Bugzilla referenced in commit '3cf71bc9904d ("drm/i915: Re- > > apply > > Perform link quality check, unconditionally during long pulse"")', > > the > > issue is that the sink does not trigger an interrupt. We want the > > ->detect() from user space to check link status and retrain. > > Ville's > > review for the original patch also indicates the same root cause. > > > > I have also renamed long_pulse() to full_detect(). > > have you?! > I just see the comment change on this patch ;) > > > > v2: Patch split and rewrote comment.. I split the renaming part. I'll rewrite the commit message if you want me to. > > > > Cc: Lyude Paul <lyude@redhat.com> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > > Cc: Jani Nikula <jani.nikula@linux.intel.com> > > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> > > Cc: Jan-Marek Glogowski <glogow@fbihome.de> > > References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link quality > > check, unconditionally during long pulse"") > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> > > --- > > drivers/gpu/drm/i915/intel_dp.c | 12 ++---------- > > 1 file changed, 2 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/intel_dp.c > > b/drivers/gpu/drm/i915/intel_dp.c > > index 436c22de33b6..cac1c7c6cbfd 100644 > > --- a/drivers/gpu/drm/i915/intel_dp.c > > +++ b/drivers/gpu/drm/i915/intel_dp.c > > @@ -5074,16 +5074,8 @@ intel_dp_long_pulse(struct intel_connector > > *connector, > > goto out; > > } else { > > /* > > - * If display is now connected check links status, > > - * there has been known issues of link loss > > triggering > > - * 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. > > + * Some monitors do not signal loss of link > > synchronization > > + * with an IRQ_HPD, so force a link status check. > > */ > > struct intel_encoder *encoder = > > &dp_to_dig_port(intel_dp)->base; > > > > -- > > 2.14.1 > > > > _______________________________________________ > > Intel-gfx mailing list > > Intel-gfx@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 436c22de33b6..cac1c7c6cbfd 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -5074,16 +5074,8 @@ intel_dp_long_pulse(struct intel_connector *connector, goto out; } else { /* - * If display is now connected check links status, - * there has been known issues of link loss triggering - * 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. + * Some monitors do not signal loss of link synchronization + * with an IRQ_HPD, so force a link status check. */ struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
Comment claims link needs to be retrained because the connected sink raised a long pulse to indicate link loss. If the sink did so, intel_dp_hotplug() would have handled link retraining. Looking at the logs in Bugzilla referenced in commit '3cf71bc9904d ("drm/i915: Re-apply Perform link quality check, unconditionally during long pulse"")', the issue is that the sink does not trigger an interrupt. We want the ->detect() from user space to check link status and retrain. Ville's review for the original patch also indicates the same root cause. I have also renamed long_pulse() to full_detect(). v2: Patch split and rewrote comment.. Cc: Lyude Paul <lyude@redhat.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Jan-Marek Glogowski <glogow@fbihome.de> References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse"") Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com> --- drivers/gpu/drm/i915/intel_dp.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-)