[PATCH v3 07/12] drm/msm/dp: Implement hpd_notify()

[Bjorn Andersson <quic_bjorande@quicinc.com>]

From: Bjorn Andersson <bjorn.andersson@linaro.org>

The DisplayPort controller's hot-plug mechanism is based on pinmuxing a
physical signal on a GPIO pin into the controller. This is not always
possible, either because there aren't dedicated GPIOs available or
because the hot-plug signal is a virtual notification, in cases such as
USB Type-C.

For these cases, by implementing the hpd_notify() callback for the
DisplayPort controller's drm_bridge, a downstream drm_bridge
(next_bridge) can be used to track and signal the connection status
changes.

This makes it possible to use downstream drm_bridges such as
display-connector or any virtual mechanism, as long as they are
implemented as a drm_bridge.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
[bjorn: Drop connector->fwnode assignment and dev from struct msm_dp]
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
---

Changes since v2:
- Fixed spelling of "on a GPIO" in commit message

 drivers/gpu/drm/msm/dp/dp_display.c | 22 ++++++++++++++++++++++
 drivers/gpu/drm/msm/dp/dp_drm.c     |  1 +
 drivers/gpu/drm/msm/dp/dp_drm.h     |  2 ++
 3 files changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 699f28f2251e..a4563a0753b0 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1765,3 +1765,25 @@ void dp_bridge_mode_set(struct drm_bridge *drm_bridge,
 	dp_display->dp_mode.h_active_low =
 		!!(dp_display->dp_mode.drm_mode.flags & DRM_MODE_FLAG_NHSYNC);
 }
+
+void dp_bridge_hpd_notify(struct drm_bridge *bridge,
+			  enum drm_connector_status status)
+{
+	struct msm_dp_bridge *dp_bridge = to_dp_bridge(bridge);
+	struct msm_dp *dp_display = dp_bridge->dp_display;
+	struct dp_display_private *dp = container_of(dp_display, struct dp_display_private, dp_display);
+
+	/* Without next_bridge interrupts are handled by the DP core directly */
+	if (!dp_display->next_bridge)
+		return;
+
+	if (!dp->core_initialized) {
+		drm_dbg_dp(dp->drm_dev, "not initialized\n");
+		return;
+	}
+
+	if (!dp_display->is_connected && status == connector_status_connected)
+		dp_add_event(dp, EV_HPD_PLUG_INT, 0, 0);
+	else if (dp_display->is_connected && status == connector_status_disconnected)
+		dp_add_event(dp, EV_HPD_UNPLUG_INT, 0, 0);
+}
diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index 6df25f7662e7..1a02ec029fdd 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_drm.c
@@ -68,6 +68,7 @@ static const struct drm_bridge_funcs dp_bridge_ops = {
 	.mode_valid   = dp_bridge_mode_valid,
 	.get_modes    = dp_bridge_get_modes,
 	.detect       = dp_bridge_detect,
+	.hpd_notify   = dp_bridge_hpd_notify,
 };
 
 struct drm_bridge *dp_bridge_init(struct msm_dp *dp_display, struct drm_device *dev,
diff --git a/drivers/gpu/drm/msm/dp/dp_drm.h b/drivers/gpu/drm/msm/dp/dp_drm.h
index 82035dbb0578..79e6b2cf2d25 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.h
+++ b/drivers/gpu/drm/msm/dp/dp_drm.h
@@ -32,5 +32,7 @@ enum drm_mode_status dp_bridge_mode_valid(struct drm_bridge *bridge,
 void dp_bridge_mode_set(struct drm_bridge *drm_bridge,
 			const struct drm_display_mode *mode,
 			const struct drm_display_mode *adjusted_mode);
+void dp_bridge_hpd_notify(struct drm_bridge *bridge,
+			  enum drm_connector_status status);
 
 #endif /* _DP_DRM_H_ */
-- 
2.37.3