drm/i915: Avoid HPD poll detect triggering a new detect cycle

For the HPD interrupt functionality the HW depends on power wells in the
display core domain to be on. Accordingly when enabling these power
wells the HPD polling logic will force an HPD detection cycle to account
for hotplug events that may have happened when such a power well was
off.

Thus a detect cycle started by polling could start a new detect cycle if
a power well in the display core domain gets enabled during detect and
stays enabled after detect completes. That in turn can lead to a
detection cycle runaway.

To prevent re-triggering a poll-detect cycle make sure we drop all power
references we acquired during detect synchronously by the end of detect.
This will let the poll-detect logic continue with polling (matching the
off state of the corresponding power wells) instead of scheduling a new
detection cycle.

Fixes: 6cfe7ec02e85 ("drm/i915: Remove the unneeded AUX power ref from intel_dp_detect()")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112125
Reported-and-tested-by: Val Kulkov <val.kulkov@gmail.com>
Reported-and-tested-by: wangqr <wqr.prg@gmail.com>
Cc: Val Kulkov <val.kulkov@gmail.com>
Cc: wangqr <wqr.prg@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191028181517.22602-1-imre.deak@intel.com
(cherry picked from commit a8ddac7c9f06a12227a4f5febd1cbe0575a33179)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_crt.c b/drivers/gpu/drm/i915/display/intel_crt.c
index e6e8d4a820446a7fd99f7b7af735a378d8d0918e..0a08354a61836af78bd47c08c090ba2cc1c75b85 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_crt.c
+++ b/drivers/gpu/drm/i915/display/intel_crt.c
@@ -864,6 +864,13 @@ load_detect:
 
 out:
        intel_display_power_put(dev_priv, intel_encoder->power_domain, wakeref);
+
+       /*
+        * Make sure the refs for power wells enabled during detect are
+        * dropped to avoid a new detect cycle triggered by HPD polling.
+        */
+       intel_display_power_flush_work(dev_priv);
+
        return status;
 }
 

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 57e9f0ba331b4e7a31ecd4898dfc5410020c3980..2822a9f198440910d36d45ea3081235cbe9d3ea7 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5436,6 +5436,12 @@ out:
        if (status != connector_status_connected && !intel_dp->is_mst)
                intel_dp_unset_edid(intel_dp);
 
+       /*
+        * Make sure the refs for power wells enabled during detect are
+        * dropped to avoid a new detect cycle triggered by HPD polling.
+        */
+       intel_display_power_flush_work(dev_priv);
+
        return status;
 }
 

diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index e02f0faecf02806235df03dbe870ec88dd9b5a73..b030f7ae330290393f3fe7136ccc078503b33828 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -2565,6 +2565,12 @@ out:
        if (status != connector_status_connected)
                cec_notifier_phys_addr_invalidate(intel_hdmi->cec_notifier);
 
+       /*
+        * Make sure the refs for power wells enabled during detect are
+        * dropped to avoid a new detect cycle triggered by HPD polling.
+        */
+       intel_display_power_flush_work(dev_priv);
+
        return status;
 }