[Intel-gfx] [PATCH 03/12] drm/i915: Add EDID read in intel_dp_check_link_status() for Link CTS 4.2.2.1

[Todd Previte]

Adds in an EDID read after the DPCD read to accommodate test 4.2.2.1 in the
Displayport Link CTS Core 1.2 rev1.1. This test requires an EDID read for
all HPD plug events. To reduce the amount of code, this EDID read is also
used for Link CTS tests 4.2.2.3, 4.2.2.4, 4.2.2.5 and 4.2.2.6. Actual
support for these tests is implemented in later patches in this series.

V2:
- Fixed compilation error introduced during rework
V3:
- Plugged a memory leak where the EDID data wasn't being freed
  after allocation in this function
V4:
- Fixed whitespace problems
- Cleaned up formatting
V5:
- Added propagation of the long_hpd flag from the hot_pulse function

Signed-off-by: Todd Previte <tprevite at gmail.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 1352c00..23586f6 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4110,15 +4110,30 @@ go_again:
  *  4. Check link status on receipt of hot-plug interrupt
  */
 static void
-intel_dp_check_link_status(struct intel_dp *intel_dp)
+intel_dp_check_link_status(struct intel_dp *intel_dp, bool long_hpd)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
+	struct drm_connector *connector = &intel_dp->attached_connector->base;
+	struct i2c_adapter *adapter = &intel_dp->aux.ddc;
+	struct edid *edid_read = NULL;
 	u8 sink_irq_vector;
 	u8 link_status[DP_LINK_STATUS_SIZE];
 
 	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 
+	/* Displayport Link CTS Core 1.2 rev1.1 EDID testing
+	 * 4.2.2.1 - EDID read required for all HPD events
+	 */
+	if (long_hpd) {
+		edid_read = drm_get_edid(connector, adapter);
+		if (!edid_read) {
+			DRM_DEBUG_DRIVER("Invalid EDID detected\n");
+		} else {
+			kfree(edid_read);
+		}
+	}
+
 	/* Try to read the source of the interrupt */
 	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
 	    intel_dp_get_sink_irq(intel_dp, &sink_irq_vector)) {
@@ -4773,7 +4788,7 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 			 * 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);
+			intel_dp_check_link_status(intel_dp, long_hpd);
 			drm_modeset_unlock(&dev->mode_config.connection_mutex);
 		}
 	}
-- 
1.9.1