[PATCH 4.2.y-ckt 120/268] drm/i915: intel_hpd_init(): Fix suspend/resume reprobing

From: Kamal Mostafa
Date: Wed Jan 27 2016 - 16:33:15 EST

4.2.8-ckt3 -stable review patch. If anyone has any objections, please let me know.


From: Lyude <cpaul@xxxxxxxxxx>

commit 2dc2f761dea65069485110d24eaa5b0d5d808b07 upstream.

This fixes reprobing of display connectors on resume. 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
- 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.

In addition, we also now avoid setting connector->polled to
DRM_CONNECTOR_POLL_HPD for MST connectors, since their reprobing is
handled by the mst helpers. This is probably what was originally
intended to happen here.

Changes since V1:
* Use the explanation of the issue as the commit message instead
* Change the title of the commit, since this does more then just stop a
check for an encoder now
* Add "Fixes" line for the patch that introduced this regression
* Don't enable DRM_CONNECTOR_POLL_HPD for mst connectors

Changes since V2:
* Put patch changelog above Signed-off-by
* Follow Daniel Vetter's suggestion for making the code here a bit more

Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
Signed-off-by: Lyude <cpaul@xxxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1452181408-14777-1-git-send-email-cpaul@xxxxxxxxxx
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
(cherry picked from commit 07c519134417d92c2e1a536e2b66d4ffff4b3be0)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
drivers/gpu/drm/i915/i915_irq.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 984e2fe..6a51bc6 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -4447,9 +4447,14 @@ 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)
- connector->polled = DRM_CONNECTOR_POLL_HPD;
+ /* MST has a dynamic intel_connector->encoder and it's reprobing
+ * is all handled by the MST helpers. */
if (intel_connector->mst_port)
+ continue;
+ if (!connector->polled && I915_HAS_HOTPLUG(dev) &&
+ intel_connector->encoder->hpd_pin > HPD_NONE)
connector->polled = DRM_CONNECTOR_POLL_HPD;