[PATCH 7/7][SRU][OEM-B][B] drm/i915: Enable hotplug retry

[You-Sheng Yang]

From: José Roberto de Souza <jose.souza at intel.com>

BugLink: http://bugs.launchpad.net/bugs/1835001

Right now we are aware of two cases that needs another hotplug retry:
- Unpowered type-c dongles
- HDMI slow unplug

Both have a complete explanation in the code to schedule another run
of the hotplug handler.

It could have more checks to just trigger the retry in those two
specific cases but why would sink signal a long pulse if there is
no change? Also the drawback of running the hotplug handler again
is really low and that could fix another cases that we are not
aware.

Also retrying for old DP ports(non-DDI) to make it consistent and not
cause CI failures if those systems are connected to chamelium boards
that will be used to simulate the issues reported in here.

v2: Also retrying for old DP ports(non-DDI)(Imre)

v4: Renamed INTEL_HOTPLUG_NOCHANGE to INTEL_HOTPLUG_UNCHANGED to keep
it consistent(Rodrigo)

Tested-by: Timo Aaltonen <tjaalton at ubuntu.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Imre Deak <imre.deak at intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
Reviewed-by: Imre Deak <imre.deak at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190712005343.24571-2-jose.souza@intel.com
(backported from commit bb80c9255770fa1ed54e889a6bee628bdd0f6762
git://anongit.freedesktop.org/drm-intel)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
---
 drivers/gpu/drm/i915/intel_ddi.c  | 21 +++++++++++++++++++++
 drivers/gpu/drm/i915/intel_dp.c   |  7 +++++++
 drivers/gpu/drm/i915/intel_hdmi.c | 28 +++++++++++++++++++++++++++-
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 5aac71f23b2f..af60d03a2085 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -2825,6 +2825,7 @@ intel_ddi_hotplug(struct intel_encoder *encoder,
 		  struct intel_connector *connector,
 		  bool irq_received)
 {
+	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
 	struct drm_modeset_acquire_ctx ctx;
 	enum intel_hotplug_state state;
 	int ret;
@@ -2851,6 +2852,26 @@ intel_ddi_hotplug(struct intel_encoder *encoder,
 	drm_modeset_acquire_fini(&ctx);
 	WARN(ret, "Acquiring modeset locks failed with %i\n", ret);
 
+	/*
+	 * Unpowered type-c dongles can take some time to boot and be
+	 * responsible, so here giving some time to those dongles to power up
+	 * and then retrying the probe.
+	 *
+	 * On many platforms the HDMI live state signal is known to be
+	 * unreliable, so we can't use it to detect if a sink is connected or
+	 * not. Instead we detect if it's connected based on whether we can
+	 * read the EDID or not. That in turn has a problem during disconnect,
+	 * since the HPD interrupt may be raised before the DDC lines get
+	 * disconnected (due to how the required length of DDC vs. HPD
+	 * connector pins are specified) and so we'll still be able to get a
+	 * valid EDID. To solve this schedule another detection cycle if this
+	 * time around we didn't detect any change in the sink's connection
+	 * status.
+	 */
+	if (state == INTEL_HOTPLUG_UNCHANGED && irq_received &&
+	    !dig_port->dp.is_mst)
+		state = INTEL_HOTPLUG_RETRY;
+
 	return state;
 }
 
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 27076de4e4ae..0b0e104af88e 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4385,6 +4385,13 @@ intel_dp_hotplug(struct intel_encoder *encoder,
 	drm_modeset_acquire_fini(&ctx);
 	WARN(ret, "Acquiring modeset locks failed with %i\n", ret);
 
+	/*
+	 * Keeping it consistent with intel_ddi_hotplug() and
+	 * intel_hdmi_hotplug().
+	 */
+	if (state == INTEL_HOTPLUG_UNCHANGED && irq_received)
+		state = INTEL_HOTPLUG_RETRY;
+
 	return state;
 }
 
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index e4659cf6d420..e6f652005df6 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -2064,6 +2064,32 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
 	}
 }
 
+static enum intel_hotplug_state
+intel_hdmi_hotplug(struct intel_encoder *encoder,
+		   struct intel_connector *connector, bool irq_received)
+{
+	enum intel_hotplug_state state;
+
+	state = intel_encoder_hotplug(encoder, connector, irq_received);
+
+	/*
+	 * On many platforms the HDMI live state signal is known to be
+	 * unreliable, so we can't use it to detect if a sink is connected or
+	 * not. Instead we detect if it's connected based on whether we can
+	 * read the EDID or not. That in turn has a problem during disconnect,
+	 * since the HPD interrupt may be raised before the DDC lines get
+	 * disconnected (due to how the required length of DDC vs. HPD
+	 * connector pins are specified) and so we'll still be able to get a
+	 * valid EDID. To solve this schedule another detection cycle if this
+	 * time around we didn't detect any change in the sink's connection
+	 * status.
+	 */
+	if (state == INTEL_HOTPLUG_UNCHANGED && irq_received)
+		state = INTEL_HOTPLUG_RETRY;
+
+	return state;
+}
+
 void intel_hdmi_init(struct drm_i915_private *dev_priv,
 		     i915_reg_t hdmi_reg, enum port port)
 {
@@ -2087,7 +2113,7 @@ void intel_hdmi_init(struct drm_i915_private *dev_priv,
 			 &intel_hdmi_enc_funcs, DRM_MODE_ENCODER_TMDS,
 			 "HDMI %c", port_name(port));
 
-	intel_encoder->hotplug = intel_encoder_hotplug;
+	intel_encoder->hotplug = intel_hdmi_hotplug;
 	intel_encoder->compute_config = intel_hdmi_compute_config;
 	if (HAS_PCH_SPLIT(dev_priv)) {
 		intel_encoder->disable = pch_disable_hdmi;
-- 
2.20.1