[Intel-gfx] [PATCH 06/12] drm/i915: Update intel_dp_hpd_pulse() for non-MST operation

[Todd Previte]

Update the hot plug function to handle the SST case. Instead of placing
the SST case within the long/short pulse block, it is now handled after
determining that MST mode is not in use. This way, the topology management
layer can handle any MST-related operations while SST operations are still
correctly handled afterwards.

This patch also corrects the problem of SST mode only being handled in the
case of a short (0.5ms - 1.0ms) HPD pulse. For compliance testing purposes
both short and long pulses are used by the different tests, thus both cases
need to be addressed for SST.

This patch replaces [PATCH 10/10] drm/i915: Fix intel_dp_hot_plug() in the
previous compliance testing patch sequence. Review feedback on that patch
indicated that updating intel_dp_hot_plug() was not the correct place for
the test handler.

For the SST case, the main stream is disabled for long HPD pulses as this
generally indicates either a connect/disconnect event or link failure. For
a number of case in compliance testing, the source is required to disable
the main link upon detection of a long HPD.

V2:
- N/A
V3:
- Place the SST mode link status check into the mst_fail case
- Remove obsolete comment regarding SST mode operation
- Removed an erroneous line of code that snuck in during rebasing
V4:
- Added a disable of the main stream (DP transport) for the long pulse case
  for SST to support compliance testing
V5:
- Reworked SST handling to support tests 4.2.2.7 and 4.2.2.8
V6:
- Reformatted a comment
V7:
- Moved a comment again that was inadvertently moved
- Updated the code to properly handle all permutations of MST/SST and
  short/long pulse.
- Adds a new 'connected' flag that prevents unnecessary operations when
  the link is disconnected.
- Added a function to encapsulate detection of the HPD pin status in
  in order to determine connected status
- Reformatted the if-statements in the function so the braces are
  consistent for those with single statements after the if-statement
V8:
- Updated to account for long_hpd flag propagation

Signed-off-by: Todd Previte <tprevite at gmail.com>
---
 drivers/gpu/drm/i915/intel_dp.c  | 55 +++++++++++++++++++++++++---------------
 drivers/gpu/drm/i915/intel_drv.h |  1 +
 2 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ee41e10..aa3b89d 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4747,6 +4747,7 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	enum intel_display_power_domain power_domain;
 	enum irqreturn ret = IRQ_NONE;
+	bool connected = false;
 
 	if (intel_dig_port->base.type != INTEL_OUTPUT_EDP)
 		intel_dig_port->base.type = INTEL_OUTPUT_DISPLAYPORT;
@@ -4770,19 +4771,15 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 	power_domain = intel_display_port_power_domain(intel_encoder);
 	intel_display_power_get(dev_priv, power_domain);
 
+	connected = intel_dp_digital_port_connected(intel_dp);
+
 	if (long_hpd) {
 
-		if (HAS_PCH_SPLIT(dev)) {
-			if (!ibx_digital_port_connected(dev_priv, intel_dig_port))
-				goto mst_fail;
-		} else {
-			if (g4x_digital_port_connected(dev, intel_dig_port) != 1)
-				goto mst_fail;
-		}
+		if (!connected)
+			goto mst_fail;
 
-		if (!intel_dp_get_dpcd(intel_dp)) {
+		if (!intel_dp_get_dpcd(intel_dp))
 			goto mst_fail;
-		}
 
 		intel_dp_probe_oui(intel_dp);
 
@@ -4790,20 +4787,9 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 			goto mst_fail;
 
 	} else {
-		if (intel_dp->is_mst) {
+		if (intel_dp->is_mst)
 			if (intel_dp_check_mst_status(intel_dp) == -EINVAL)
 				goto mst_fail;
-		}
-
-		if (!intel_dp->is_mst) {
-			/*
-			 * we'll check the link status via the normal hot plug path later -
-			 * but for short hpds we should check it now
-			 */
-			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
-			intel_dp_check_link_status(intel_dp, long_hpd);
-			drm_modeset_unlock(&dev->mode_config.connection_mutex);
-		}
 	}
 
 	ret = IRQ_HANDLED;
@@ -4817,6 +4803,15 @@ mst_fail:
 		drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
 	}
 put_power:
+	/* SST mode - handle short/long pulses here */
+	if (!intel_dp->is_mst) {
+
+		drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+		if (connected)
+			intel_dp_check_link_status(intel_dp, long_hpd);
+		drm_modeset_unlock(&dev->mode_config.connection_mutex);
+		ret = IRQ_HANDLED;
+	}
 	intel_display_power_put(dev_priv, power_domain);
 
 	return ret;
@@ -5803,3 +5798,21 @@ void intel_dp_mst_resume(struct drm_device *dev)
 		}
 	}
 }
+
+bool intel_dp_digital_port_connected(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct drm_device *dev = intel_dig_port->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	bool connected = true;
+
+	if (HAS_PCH_SPLIT(dev)) {
+		if (!ibx_digital_port_connected(dev_priv, intel_dig_port))
+			connected = false;
+	} else {
+		if (g4x_digital_port_connected(dev, intel_dig_port) != 1)
+			connected = false;
+	}
+
+	return connected;
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index a4675fa..accf08b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1173,6 +1173,7 @@ void intel_edp_drrs_disable(struct intel_dp *intel_dp);
 void intel_edp_drrs_invalidate(struct drm_device *dev,
 		unsigned frontbuffer_bits);
 void intel_edp_drrs_flush(struct drm_device *dev, unsigned frontbuffer_bits);
+bool intel_dp_digital_port_connected(struct intel_dp *intel_dp);
 
 /* intel_dp_mst.c */
 int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
-- 
1.9.1