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authorDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>2018-09-27 22:57:30 +0200
committerJoonas Lahtinen <joonas.lahtinen@linux.intel.com>2018-10-24 12:46:57 +0200
commit49af5d95b9b3c21a84ad115a9db9acbc036d849a (patch)
tree91cc7bcc227595125fcec6a0213c47044c1e79ad /drivers/gpu
parentdrm/nouveau: Fix nv50_mstc->best_encoder() (diff)
downloadlinux-49af5d95b9b3c21a84ad115a9db9acbc036d849a.tar.xz
linux-49af5d95b9b3c21a84ad115a9db9acbc036d849a.zip
drm/i915/dp: Fix link retraining comment in intel_dp_long_pulse()
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. What we want is ->detect() from user space to check link status and retrain. Ville's review for the original patch also indicates the same root cause. So, rewrite the comment. 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> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180927205735.16651-1-dhinakaran.pandiyan@intel.com (cherry picked from commit 9ebd8202393dde9d3678c9ec162c1aa63ba17eac) Fixes: 399334708b4f ("drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse"") Cc: stable@vger.kernel.org Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Diffstat (limited to 'drivers/gpu')
-rw-r--r--drivers/gpu/drm/i915/intel_dp.c13
1 files changed, 3 insertions, 10 deletions
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 3fae4dab295f..e2a1af0a3492 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5104,16 +5104,9 @@ 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 external 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;