[PATCH v2 13/13] drm/vc4: hdmi: Reset link on hotplug

[Maxime Ripard <maxime@cerno.tech>]

Enabling the scrambling on reconnection seems to work so far but breaks
the HDMI2.0 specification and has introduced some issues in the past
with i915.

Let's do a mode set on the connector instead to follow the
specification.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index ba939dab35c0..57310756d2cc 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -175,9 +175,8 @@ static void vc4_hdmi_cec_update_clk_div(struct vc4_hdmi *vc4_hdmi)
 static void vc4_hdmi_cec_update_clk_div(struct vc4_hdmi *vc4_hdmi) {}
 #endif
 
-static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder);
-
 static void vc4_hdmi_handle_hotplug(struct vc4_hdmi *vc4_hdmi,
+				    struct drm_modeset_acquire_ctx *ctx,
 				    enum drm_connector_status status)
 {
 	struct drm_connector *connector = &vc4_hdmi->connector;
@@ -190,6 +189,10 @@ static void vc4_hdmi_handle_hotplug(struct vc4_hdmi *vc4_hdmi,
 	 * .adap_enable, which leads to that funtion being called with
 	 * our mutex held.
 	 *
+	 * A similar situation occurs with
+	 * drm_atomic_helper_connector_hdmi_reset_link() that will call
+	 * into our KMS hooks if the scrambling was enabled.
+	 *
 	 * Concurrency isn't an issue at the moment since we don't share
 	 * any state with any of the other frameworks so we can ignore
 	 * the lock for now.
@@ -210,7 +213,7 @@ static void vc4_hdmi_handle_hotplug(struct vc4_hdmi *vc4_hdmi,
 	cec_s_phys_addr_from_edid(vc4_hdmi->cec_adap, edid);
 	kfree(edid);
 
-	vc4_hdmi_enable_scrambling(&vc4_hdmi->encoder.base.base);
+	drm_atomic_helper_connector_hdmi_reset_link(connector, ctx);
 }
 
 static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
@@ -248,7 +251,7 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
 			status = connector_status_connected;
 	}
 
-	vc4_hdmi_handle_hotplug(vc4_hdmi, status);
+	vc4_hdmi_handle_hotplug(vc4_hdmi, ctx, status);
 	pm_runtime_put(&vc4_hdmi->pdev->dev);
 
 	return status;
-- 
2.33.1