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

diff --git a/drivers/gpu/drm/i915/display/intel_crt.c b/drivers/gpu/drm/i915/display/intel_crt.c
index ff6126ea793ceba3eed90c0f676ca0f212247097..834bf1d43bb8dba5e02dd1907a91045b231835c6 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_crt.c
+++ b/drivers/gpu/drm/i915/display/intel_crt.c
@@ -864,6 +864,13 @@ intel_crt_detect(struct drm_connector *connector,
 
 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 325b70bb140d35bb2cf60b5a3d9b4a2db4361a48..077cc25b7051f4a382c9f61ef6b58960c23a212b 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5693,6 +5693,12 @@ intel_dp_detect(struct drm_connector *connector,
        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 b54ccbb5aad5a63ccd207ac3ac97e5e09728da43..ff71a4da3d002bf11fc77fb5f729c0359a62bdc7 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -2626,6 +2626,12 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
        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;
 }