61 lines
2.6 KiB
Diff
61 lines
2.6 KiB
Diff
From patchwork Thu Sep 27 20:57:30 2018
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit
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Subject: [CI, 1/6] drm/i915/dp: Fix link retraining comment in
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intel_dp_long_pulse()
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From: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
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X-Patchwork-Id: 253516
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Message-Id: <20180927205735.16651-1-dhinakaran.pandiyan@intel.com>
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To: intel-gfx@lists.freedesktop.org
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Date: Thu, 27 Sep 2018 13:57:30 -0700
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Comment claims link needs to be retrained because the connected sink raised
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a long pulse to indicate link loss. If the sink did so,
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intel_dp_hotplug() would have handled link retraining. Looking at the
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logs in Bugzilla referenced in commit '3cf71bc9904d ("drm/i915: Re-apply
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Perform link quality check, unconditionally during long pulse"")', the
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issue is that the sink does not trigger an interrupt. What we want is
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->detect() from user space to check link status and retrain. Ville's
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review for the original patch also indicates the same root cause. So,
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rewrite the comment.
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v2: Patch split and rewrote comment.
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Cc: Lyude Paul <lyude@redhat.com>
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Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
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Cc: Jani Nikula <jani.nikula@linux.intel.com>
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Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
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Cc: Jan-Marek Glogowski <glogow@fbihome.de>
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References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link quality check, unconditionally during long pulse"")
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Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
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Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
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---
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drivers/gpu/drm/i915/intel_dp.c | 13 +++----------
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1 file changed, 3 insertions(+), 10 deletions(-)
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diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
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index 256a71c8c093..207b3ea2ed1a 100644
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--- a/drivers/gpu/drm/i915/intel_dp.c
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+++ b/drivers/gpu/drm/i915/intel_dp.c
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@@ -5074,16 +5074,9 @@ intel_dp_long_pulse(struct intel_connector *connector,
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goto out;
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} else {
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/*
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- * If display is now connected check links status,
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- * there has been known issues of link loss triggering
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- * long pulse.
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- *
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- * Some sinks (eg. ASUS PB287Q) seem to perform some
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- * weird HPD ping pong during modesets. So we can apparently
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- * end up with HPD going low during a modeset, and then
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- * going back up soon after. And once that happens we must
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- * retrain the link to get a picture. That's in case no
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- * userspace component reacted to intermittent HPD dip.
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+ * Some external monitors do not signal loss of link
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+ * synchronization with an IRQ_HPD, so force a link status
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+ * check.
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*/
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struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
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