linux-kernel - [PATCH] drm/i915: intel_hpd_init(): Don't check connectors for an encoder

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Date:	Tue,  5 Jan 2016 14:53:08 -0500
From:	Lyude <cpaul@...hat.com>
To:	Daniel Vetter <daniel.vetter@...el.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	David Airlie <airlied@...ux.ie>,
	intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Cc:	Benjamin Tissoires <btissoir@...hat.com>, Lyude <cpaul@...hat.com>
Subject: [PATCH] drm/i915: intel_hpd_init(): Don't check connectors for an encoder

There's no reason to check for an active encoder when setting up hpd,
especially since a disconnected connector isn't going to have an encoder
in the first place. This fixes reprobing display connectors on resume.

Signed-off-by: Lyude <cpaul@...hat.com>
---
After some talking with danvet on IRC, I learned that calling
drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
connector's status. It turns out this is the actual reason reprobing on resume
hasn't been working (this was observed on a T440s):

	- We call hpd_init()
	- We check each connector for a couple of things before marking
	  connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
	  active encoder. Of course, a disconnected port won't have an active
	  encoder, so we don't add the flag to any of the connector's.
	- We call drm_helper_hpd_irq_event()
	- drm_helper_irq_event() checks each connector for the
	  DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1, so we
	  skip reprobing each connector except that one.

 drivers/gpu/drm/i915/intel_hotplug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index b177857..18797bc 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -468,7 +468,7 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
 	list_for_each_entry(connector, &mode_config->connector_list, head) {
 		struct intel_connector *intel_connector = to_intel_connector(connector);
 		connector->polled = intel_connector->polled;
-		if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
+		if (!connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
 			connector->polled = DRM_CONNECTOR_POLL_HPD;
 		if (intel_connector->mst_port)
 			connector->polled = DRM_CONNECTOR_POLL_HPD;
-- 
2.5.0

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