[RFC PATCH 0/4] drm/msm/dp: implement HPD notifications handling

[RFC PATCH 0/4] drm/msm/dp: implement HPD notifications handling

[Dmitry Baryshkov]

USB altmodes code would send OOB notifications to the drm_connector
specified in the device tree. However as the MSM DP driver uses
drm_bridge_connector, there is no way to receive these event directly.
Implement a bridge between oob_hotplug_event and drm_bridge's hpd_notify
and use it to deliver altmode messages to the MSM DP driver

Bjorn Andersson (2):
  drm: Add HPD state to drm_connector_oob_hotplug_event()
  drm/msm/dp: Implement hpd_notify()

Dmitry Baryshkov (2):
  drm/bridge_connector: stop filtering events in
    drm_bridge_connector_hpd_cb()
  drm/bridge_connector: implement oob_hotplug_event

 drivers/gpu/drm/drm_bridge_connector.c   | 17 ++++++++++++-----
 drivers/gpu/drm/drm_connector.c          |  6 ++++--
 drivers/gpu/drm/i915/display/intel_dp.c  | 17 ++++++++++++++---
 drivers/gpu/drm/i915/i915_drv.h          |  3 +++
 drivers/gpu/drm/msm/dp/dp_display.c      | 11 +++++++++++
 drivers/gpu/drm/msm/dp/dp_display.h      |  1 +
 drivers/gpu/drm/msm/dp/dp_drm.c          |  3 +++
 drivers/gpu/drm/msm/dp/dp_drm.h          |  2 ++
 drivers/gpu/drm/msm/dp/dp_hpd.c          | 21 +++++++++++++++++++++
 drivers/gpu/drm/msm/dp/dp_hpd.h          |  5 +++++
 drivers/usb/typec/altmodes/displayport.c | 10 +++-------
 include/drm/drm_connector.h              |  6 ++++--
 12 files changed, 83 insertions(+), 19 deletions(-)

-- 
2.35.1

[RFC PATCH 1/4] drm/bridge_connector: stop filtering events in drm_bridge_connector_hpd_cb()

[Dmitry Baryshkov]

In some cases the bridge drivers would like to receive hotplug events
even in the case new status is equal to the old status. In the DP case
this is used to deliver "attention" messages to the DP host. Stop
filtering the events in the drm_bridge_connector_hpd_cb() and let
drivers decide whether they would like to receive the event or not.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/drm_bridge_connector.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
index 60923cdfe8e1..a0b742ebb330 100644
--- a/drivers/gpu/drm/drm_bridge_connector.c
+++ b/drivers/gpu/drm/drm_bridge_connector.c
@@ -113,16 +113,11 @@ static void drm_bridge_connector_hpd_cb(void *cb_data,
 	struct drm_bridge_connector *drm_bridge_connector = cb_data;
 	struct drm_connector *connector = &drm_bridge_connector->base;
 	struct drm_device *dev = connector->dev;
-	enum drm_connector_status old_status;
 
 	mutex_lock(&dev->mode_config.mutex);
-	old_status = connector->status;
 	connector->status = status;
 	mutex_unlock(&dev->mode_config.mutex);
 
-	if (old_status == status)
-		return;
-
 	drm_bridge_connector_hpd_notify(connector, status);
 
 	drm_kms_helper_hotplug_event(dev);
-- 
2.35.1

[RFC PATCH 2/4] drm: Add HPD state to drm_connector_oob_hotplug_event()

[Dmitry Baryshkov]

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

In some implementations, such as the Qualcomm platforms, the display
driver has no way to query the current HPD state and as such it's
impossible to distinguish between disconnect and attention events.

Add a parameter to drm_connector_oob_hotplug_event() to pass the HPD
state.

Also push the test for unchanged state in the displayport altmode driver
into the i915 driver, to allow other drivers to act upon each update.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
[DB: replaced drm_connector_hpd_state with drm_connector_status]
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/drm_connector.c          |  6 ++++--
 drivers/gpu/drm/i915/display/intel_dp.c  | 17 ++++++++++++++---
 drivers/gpu/drm/i915/i915_drv.h          |  3 +++
 drivers/usb/typec/altmodes/displayport.c | 10 +++-------
 include/drm/drm_connector.h              |  6 ++++--
 5 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 76a8c707c34b..ae8b80bc050d 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2828,6 +2828,7 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
 /**
  * drm_connector_oob_hotplug_event - Report out-of-band hotplug event to connector
  * @connector_fwnode: fwnode_handle to report the event on
+ * @hpd_state: hot plug detect logical state
  *
  * On some hardware a hotplug event notification may come from outside the display
  * driver / device. An example of this is some USB Type-C setups where the hardware
@@ -2837,7 +2838,8 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
  * This function can be used to report these out-of-band events after obtaining
  * a drm_connector reference through calling drm_connector_find_by_fwnode().
  */
-void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode)
+void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
+				     enum drm_connector_status status)
 {
 	struct drm_connector *connector;
 
@@ -2846,7 +2848,7 @@ void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode)
 		return;
 
 	if (connector->funcs->oob_hotplug_event)
-		connector->funcs->oob_hotplug_event(connector);
+		connector->funcs->oob_hotplug_event(connector, status);
 
 	drm_connector_put(connector);
 }
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index d667657e3606..2acfc068ff51 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -4825,15 +4825,26 @@ static int intel_dp_connector_atomic_check(struct drm_connector *conn,
 	return intel_modeset_synced_crtcs(state, conn);
 }
 
-static void intel_dp_oob_hotplug_event(struct drm_connector *connector)
+static void intel_dp_oob_hotplug_event(struct drm_connector *connector,
+				       enum drm_connector_hpd_state hpd_state)
 {
 	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
 	struct drm_i915_private *i915 = to_i915(connector->dev);
+	bool hpd_high = hpd_state == DRM_CONNECTOR_HPD_HIGH;
+	unsigned int hpd_pin = encoder->hpd_pin;
+	bool need_work = false;
 
 	spin_lock_irq(&i915->irq_lock);
-	i915->hotplug.event_bits |= BIT(encoder->hpd_pin);
+	if (hpd_high != test_bit(hpd_pin, &i915->hotplug.oob_hotplug_last_state)) {
+		i915->hotplug.event_bits |= BIT(hpd_pin);
+
+		__assign_bit(hpd_pin, &i915->hotplug.oob_hotplug_last_state, hpd_high);
+		need_work = true;
+	}
 	spin_unlock_irq(&i915->irq_lock);
-	queue_delayed_work(system_wq, &i915->hotplug.hotplug_work, 0);
+
+	if (need_work)
+		queue_delayed_work(system_wq, &i915->hotplug.hotplug_work, 0);
 }
 
 static const struct drm_connector_funcs intel_dp_connector_funcs = {
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index fa14da84362e..e1e4ee1ab7df 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -138,6 +138,9 @@ struct i915_hotplug {
 	/* Whether or not to count short HPD IRQs in HPD storms */
 	u8 hpd_short_storm_enabled;
 
+	/* Last state reported by oob_hotplug_event for each encoder */
+	unsigned long oob_hotplug_last_state;
+
 	/*
 	 * if we get a HPD irq from DP and a HPD irq from non-DP
 	 * the non-DP HPD could block the workqueue on a mode config
diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index c1d8c23baa39..ea9cb1d71fd2 100644
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -59,7 +59,6 @@ struct dp_altmode {
 	struct typec_displayport_data data;
 
 	enum dp_state state;
-	bool hpd;
 
 	struct mutex lock; /* device lock */
 	struct work_struct work;
@@ -143,10 +142,8 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
 		if (!ret)
 			dp->state = DP_STATE_CONFIGURE;
 	} else {
-		if (dp->hpd != hpd) {
-			drm_connector_oob_hotplug_event(dp->connector_fwnode);
-			dp->hpd = hpd;
-		}
+		drm_connector_oob_hotplug_event(dp->connector_fwnode,
+						hpd ? DRM_CONNECTOR_HPD_HIGH : DRM_CONNECTOR_HPD_LOW);
 	}
 
 	return ret;
@@ -573,8 +570,7 @@ void dp_altmode_remove(struct typec_altmode *alt)
 	cancel_work_sync(&dp->work);
 
 	if (dp->connector_fwnode) {
-		if (dp->hpd)
-			drm_connector_oob_hotplug_event(dp->connector_fwnode);
+		drm_connector_oob_hotplug_event(dp->connector_fwnode, DRM_CONNECTOR_HPD_LOW);
 
 		fwnode_handle_put(dp->connector_fwnode);
 	}
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 5166186146f4..5670f7d18440 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1141,7 +1141,8 @@ struct drm_connector_funcs {
 	 * This will get called when a hotplug-event for a drm-connector
 	 * has been received from a source outside the display driver / device.
 	 */
-	void (*oob_hotplug_event)(struct drm_connector *connector);
+	void (*oob_hotplug_event)(struct drm_connector *connector,
+				  enum drm_connector_status status);
 
 	/**
 	 * @debugfs_init:
@@ -1749,7 +1750,8 @@ drm_connector_is_unregistered(struct drm_connector *connector)
 		DRM_CONNECTOR_UNREGISTERED;
 }
 
-void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode);
+void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
+				     enum drm_connector_status status);
 const char *drm_get_connector_type_name(unsigned int connector_type);
 const char *drm_get_connector_status_name(enum drm_connector_status status);
 const char *drm_get_subpixel_order_name(enum subpixel_order order);
-- 
2.35.1

[RFC PATCH 3/4] drm/bridge_connector: implement oob_hotplug_event

[Dmitry Baryshkov]

Implement the oob_hotplug_event() callback. Translate it to the the HPD
notification sent to the HPD bridge in the chain.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/drm_bridge_connector.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
index a0b742ebb330..b14af1c7ac07 100644
--- a/drivers/gpu/drm/drm_bridge_connector.c
+++ b/drivers/gpu/drm/drm_bridge_connector.c
@@ -123,6 +123,17 @@ static void drm_bridge_connector_hpd_cb(void *cb_data,
 	drm_kms_helper_hotplug_event(dev);
 }
 
+static void drm_bridge_connector_oob_hotplug_event(struct drm_connector *connector,
+						   enum drm_connector_status status)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *hpd = bridge_connector->bridge_hpd;
+
+	if (hpd)
+		drm_bridge_hpd_notify(hpd, status);
+}
+
 /**
  * drm_bridge_connector_enable_hpd - Enable hot-plug detection for the connector
  * @connector: The DRM bridge connector
@@ -233,6 +244,7 @@ static const struct drm_connector_funcs drm_bridge_connector_funcs = {
 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 	.debugfs_init = drm_bridge_connector_debugfs_init,
+	.oob_hotplug_event = drm_bridge_connector_oob_hotplug_event,
 };
 
 /* -----------------------------------------------------------------------------
-- 
2.35.1

[RFC PATCH 4/4] drm/msm/dp: Implement hpd_notify()

[Dmitry Baryshkov]

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

The Qualcomm DisplayPort driver contains traces of the necessary
plumbing to hook up USB HPD, in the form of the dp_hpd module and the
dp_usbpd_cb struct. Use this as basis for implementing the
hpd_notify() callback, by amending the dp_hpd module with the
missing logic.

Overall the solution is similar to what's done downstream, but upstream
all the code to disect the HPD notification lives on the calling side of
drm_connector_oob_hotplug_event().

drm_connector_oob_hotplug_event() performs the lookup of the
drm_connector based on fwnode, hence the need to assign the fwnode in
dp_drm_connector_init().

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
[DB: rebased to use drm_bridge_connector]
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 11 +++++++++++
 drivers/gpu/drm/msm/dp/dp_display.h |  1 +
 drivers/gpu/drm/msm/dp/dp_drm.c     |  3 +++
 drivers/gpu/drm/msm/dp/dp_drm.h     |  2 ++
 drivers/gpu/drm/msm/dp/dp_hpd.c     | 21 +++++++++++++++++++++
 drivers/gpu/drm/msm/dp/dp_hpd.h     |  5 +++++
 6 files changed, 43 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index c38832304353..31540d1409eb 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1300,6 +1300,7 @@ static int dp_display_probe(struct platform_device *pdev)
 	if (!desc)
 		return -EINVAL;
 
+	dp->dp_display.dev = &pdev->dev;
 	dp->pdev = pdev;
 	dp->name = "drm_dp";
 	dp->dp_display.connector_type = desc->connector_type;
@@ -1789,3 +1790,13 @@ 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 = dp_bridge->dp_display;
+	struct dp_display_private *dp_display = container_of(dp, struct dp_display_private, dp_display);
+
+	dp_display->usbpd->hpd_notify(dp_display->usbpd, status);
+}
diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h
index 4f9fe4d7610b..2d2614bc5a14 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.h
+++ b/drivers/gpu/drm/msm/dp/dp_display.h
@@ -11,6 +11,7 @@
 #include "disp/msm_disp_snapshot.h"
 
 struct msm_dp {
+	struct device *dev;
 	struct drm_device *drm_dev;
 	struct device *codec_dev;
 	struct drm_bridge *bridge;
diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index 62d58b9c4647..821cfd37b1fb 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,
@@ -138,6 +139,8 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
 	if (IS_ERR(connector))
 		return connector;
 
+	connector->fwnode = fwnode_handle_get(dev_fwnode(dp_display->dev));
+
 	drm_connector_attach_encoder(connector, dp_display->encoder);
 
 	return connector;
diff --git a/drivers/gpu/drm/msm/dp/dp_drm.h b/drivers/gpu/drm/msm/dp/dp_drm.h
index f4b1ed1e24f7..3b7480a86844 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_ */
diff --git a/drivers/gpu/drm/msm/dp/dp_hpd.c b/drivers/gpu/drm/msm/dp/dp_hpd.c
index db98a1d431eb..40ca91c7dabe 100644
--- a/drivers/gpu/drm/msm/dp/dp_hpd.c
+++ b/drivers/gpu/drm/msm/dp/dp_hpd.c
@@ -7,6 +7,8 @@
 
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_print.h>
 
 #include "dp_hpd.h"
 
@@ -45,6 +47,24 @@ int dp_hpd_connect(struct dp_usbpd *dp_usbpd, bool hpd)
 	return rc;
 }
 
+static void dp_hpd_hpd_notify(struct dp_usbpd *dp_usbpd,
+			     enum drm_connector_status status)
+{
+	struct dp_hpd_private *hpd_priv = container_of(dp_usbpd, struct dp_hpd_private, dp_usbpd);
+
+	DRM_DEBUG_DP("status: %d connected: %d\n", status, dp_usbpd->connected);
+
+	if (!dp_usbpd->connected && status == connector_status_connected) {
+		dp_usbpd->connected = true;
+		hpd_priv->dp_cb->configure(hpd_priv->dev);
+	} else if (status != connector_status_connected) {
+		dp_usbpd->connected = false;
+		hpd_priv->dp_cb->disconnect(hpd_priv->dev);
+	} else {
+		hpd_priv->dp_cb->attention(hpd_priv->dev);
+	}
+}
+
 struct dp_usbpd *dp_hpd_get(struct device *dev, struct dp_usbpd_cb *cb)
 {
 	struct dp_hpd_private *dp_hpd;
@@ -62,6 +82,7 @@ struct dp_usbpd *dp_hpd_get(struct device *dev, struct dp_usbpd_cb *cb)
 	dp_hpd->dp_cb = cb;
 
 	dp_hpd->dp_usbpd.connect = dp_hpd_connect;
+	dp_hpd->dp_usbpd.hpd_notify = dp_hpd_hpd_notify;
 
 	return &dp_hpd->dp_usbpd;
 }
diff --git a/drivers/gpu/drm/msm/dp/dp_hpd.h b/drivers/gpu/drm/msm/dp/dp_hpd.h
index 8feec5aa5027..ff40790831a4 100644
--- a/drivers/gpu/drm/msm/dp/dp_hpd.h
+++ b/drivers/gpu/drm/msm/dp/dp_hpd.h
@@ -29,7 +29,9 @@ enum plug_orientation {
  * @hpd_irq: Change in the status since last message
  * @alt_mode_cfg_done: bool to specify alt mode status
  * @debug_en: bool to specify debug mode
+ * @connected: cable currently connected
  * @connect: simulate disconnect or connect for debug mode
+ * @hpd_notify: deliver oob event to the usbpd code
  */
 struct dp_usbpd {
 	enum plug_orientation orientation;
@@ -41,8 +43,11 @@ struct dp_usbpd {
 	bool hpd_irq;
 	bool alt_mode_cfg_done;
 	bool debug_en;
+	bool connected;
 
 	int (*connect)(struct dp_usbpd *dp_usbpd, bool hpd);
+	void (*hpd_notify)(struct dp_usbpd *dp_usbpd,
+			  enum drm_connector_status status);
 };
 
 /**
-- 
2.35.1

Re: [Freedreno] [RFC PATCH 0/4] drm/msm/dp: implement HPD notifications handling

[Abhinav Kumar]

Adding kuogee here to keep him in the loop.

We will also review/test these.

Thanks

Abhinav

On 4/29/2022 12:29 PM, Dmitry Baryshkov wrote:
> USB altmodes code would send OOB notifications to the drm_connector
> specified in the device tree. However as the MSM DP driver uses
> drm_bridge_connector, there is no way to receive these event directly.
> Implement a bridge between oob_hotplug_event and drm_bridge's hpd_notify
> and use it to deliver altmode messages to the MSM DP driver
> 
> Bjorn Andersson (2):
>    drm: Add HPD state to drm_connector_oob_hotplug_event()
>    drm/msm/dp: Implement hpd_notify()
> 
> Dmitry Baryshkov (2):
>    drm/bridge_connector: stop filtering events in
>      drm_bridge_connector_hpd_cb()
>    drm/bridge_connector: implement oob_hotplug_event
> 
>   drivers/gpu/drm/drm_bridge_connector.c   | 17 ++++++++++++-----
>   drivers/gpu/drm/drm_connector.c          |  6 ++++--
>   drivers/gpu/drm/i915/display/intel_dp.c  | 17 ++++++++++++++---
>   drivers/gpu/drm/i915/i915_drv.h          |  3 +++
>   drivers/gpu/drm/msm/dp/dp_display.c      | 11 +++++++++++
>   drivers/gpu/drm/msm/dp/dp_display.h      |  1 +
>   drivers/gpu/drm/msm/dp/dp_drm.c          |  3 +++
>   drivers/gpu/drm/msm/dp/dp_drm.h          |  2 ++
>   drivers/gpu/drm/msm/dp/dp_hpd.c          | 21 +++++++++++++++++++++
>   drivers/gpu/drm/msm/dp/dp_hpd.h          |  5 +++++
>   drivers/usb/typec/altmodes/displayport.c | 10 +++-------
>   include/drm/drm_connector.h              |  6 ++++--
>   12 files changed, 83 insertions(+), 19 deletions(-)
>