[Intel-gfx] [PATCH 09/13] drm/i915: Setup dummy atomic state for connectors

[Matt Roper]

We want to enable/test plane updates via the atomic interface, but as
soon as we flip DRIVER_ATOMIC on, the DRM core will take some atomic
codepaths to lookup properties during drmModeGetConnector() and some of
those codepaths unconditionally dereference connector->state
(specifically when looking up the CRTC ID property in
drm_atomic_connector_get_property()).  Create a dummy connector state
for each connector at init time to ensure the DRM core doesn't try to
dereference a NULL connector->state.  The actual connector properties
will never be updated or contain useful information, but since we're
doing this specifically for testing/debug of the plane operations (and
only when a specific kernel module option is given), that shouldn't
really matter.

Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0e18879..82defd3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12368,6 +12368,7 @@ static void intel_setup_outputs(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_encoder *encoder;
+	struct drm_connector *connector;
 	bool dpd_is_edp = false;
 
 	intel_lvds_init(dev);
@@ -12498,6 +12499,33 @@ static void intel_setup_outputs(struct drm_device *dev)
 	if (SUPPORTS_TV(dev))
 		intel_tv_init(dev);
 
+	/*
+	 * FIXME:  We don't have full atomic support yet, but we want to be
+	 * able to enable/test plane updates via the atomic interface in the
+	 * meantime.  However as soon as we flip DRIVER_ATOMIC on, the DRM core
+	 * will take some atomic codepaths to lookup properties during
+	 * drmModeGetConnector() that unconditionally dereference
+	 * connector->state.
+	 *
+	 * We create a dummy connector state here for each connector to ensure
+	 * the DRM core doesn't try to dereference a NULL connector->state.
+	 * The actual connector properties will never be updated or contain
+	 * useful information, but since we're doing this specifically for
+	 * testing/debug of the plane operations (and only when a specific
+	 * kernel module option is given), that shouldn't really matter.
+	 *
+	 * Once atomic support for crtc's + connectors lands, this loop should
+	 * be removed since we'll be setting up real connector state, which
+	 * will contain Intel-specific properties.
+	 */
+	list_for_each_entry(connector,
+			    &dev->mode_config.connector_list,
+			    head) {
+		if (!WARN_ON(connector->state))
+			connector->state = kzalloc(sizeof(*connector->state),
+						   GFP_KERNEL);
+	}
+
 	intel_psr_init(dev);
 
 	for_each_intel_encoder(dev, encoder) {
-- 
1.8.5.1