[PATCH v10 28/69] drm/bridge: dw-hdmi-qp: Provide dw_hdmi_qp_hpd_notify() helper

Export dw_hdmi_qp_hpd_notify() for platform drivers to report hot-plug
detection events.  Unlike drm_helper_hpd_irq_event() which polls all
connectors, this helper targets only the affected connector and ensures
.detect_ctx() is invoked on reconnection events to trigger SCDC state
recovery.

Note that this helper may sleep, so it must only be called from a
threaded HPD interrupt handler or a work function.

Tested-by: Maud Spierings <[email protected]>
Tested-by: Diederik de Haas <[email protected]>  # NanoPC-T6 LTS, Rock 5B
Signed-off-by: Cristian Ciocaltea <[email protected]>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 37 ++++++++++++++++++++++++++++
 include/drm/bridge/dw_hdmi_qp.h              |  1 +
 2 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
index ee74266b7aa9..a2277531182c 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
@@ -28,6 +28,7 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_modes.h>
 #include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
 
 #include <media/cec.h>
 
@@ -163,6 +164,8 @@ struct dw_hdmi_qp {
 	struct regmap *regm;
 	int main_irq;
 
+	/* Written by the atomic enable/disable hooks, read locklessly by HPD */
+	struct drm_connector *curr_conn;
 	unsigned long tmds_char_rate;
 	bool no_hpd;
 };
@@ -785,6 +788,8 @@ static void dw_hdmi_qp_bridge_atomic_enable(struct drm_bridge *bridge,
 	dw_hdmi_qp_mod(hdmi, op_mode, OPMODE_DVI, LINK_CONFIG0);
 
 	drm_atomic_helper_connector_hdmi_update_infoframes(connector, state);
+
+	WRITE_ONCE(hdmi->curr_conn, connector);
 }
 
 static void dw_hdmi_qp_bridge_atomic_disable(struct drm_bridge *bridge,
@@ -793,6 +798,7 @@ static void dw_hdmi_qp_bridge_atomic_disable(struct drm_bridge *bridge,
 	struct dw_hdmi_qp *hdmi = bridge->driver_private;
 	struct drm_connector *connector;
 
+	WRITE_ONCE(hdmi->curr_conn, NULL);
 	hdmi->tmds_char_rate = 0;
 
 	connector = drm_atomic_get_old_connector_for_encoder(state, bridge->encoder);
@@ -1409,6 +1415,37 @@ struct dw_hdmi_qp *dw_hdmi_qp_bind(struct platform_device *pdev,
 }
 EXPORT_SYMBOL_GPL(dw_hdmi_qp_bind);
 
+/**
+ * dw_hdmi_qp_hpd_notify() - Notify a hot-plug detection event
+ * @hdmi: pointer to the DW HDMI QP controller
+ *
+ * Platform drivers should call this from their threaded IRQ handler or work
+ * function to notify the bridge of a connection status change.
+ * The bridge's .read_hpd() phy_ops callback is used to read the current
+ * connection status.
+ */
+void dw_hdmi_qp_hpd_notify(struct dw_hdmi_qp *hdmi)
+{
+	struct drm_connector *conn = READ_ONCE(hdmi->curr_conn);
+	enum drm_connector_status status;
+
+	status = hdmi->phy.ops->read_hpd(hdmi, hdmi->phy.data);
+	dev_dbg(hdmi->dev, "%s status=%d\n", __func__, status);
+
+	/*
+	 * When the display pipeline has been already active, switch to
+	 * drm_connector_helper_hpd_irq_event() to ensure .detect_ctx()
+	 * gets invoked, i.e. via drm_helper_probe_detect(), because
+	 * drm_bridge_hpd_notify() defers to a delayed hotplug path in
+	 * this case.
+	 */
+	if (conn && status == connector_status_connected)
+		drm_connector_helper_hpd_irq_event(conn);
+	else
+		drm_bridge_hpd_notify(&hdmi->bridge, status);
+}
+EXPORT_SYMBOL_GPL(dw_hdmi_qp_hpd_notify);
+
 void dw_hdmi_qp_suspend(struct device *dev, struct dw_hdmi_qp *hdmi)
 {
 	disable_irq(hdmi->main_irq);
diff --git a/include/drm/bridge/dw_hdmi_qp.h b/include/drm/bridge/dw_hdmi_qp.h
index b80fceffc315..b4fb1c578a5b 100644
--- a/include/drm/bridge/dw_hdmi_qp.h
+++ b/include/drm/bridge/dw_hdmi_qp.h
@@ -36,6 +36,7 @@ struct dw_hdmi_qp_plat_data {
 struct dw_hdmi_qp *dw_hdmi_qp_bind(struct platform_device *pdev,
 				   struct drm_encoder *encoder,
 				   const struct dw_hdmi_qp_plat_data *plat_data);
+void dw_hdmi_qp_hpd_notify(struct dw_hdmi_qp *hdmi);
 void dw_hdmi_qp_suspend(struct device *dev, struct dw_hdmi_qp *hdmi);
 void dw_hdmi_qp_resume(struct device *dev, struct dw_hdmi_qp *hdmi);
 #endif /* __DW_HDMI_QP__ */

-- 
2.55.0