linux-kernel - [PATCH v4 07/15] drm/bridge: Add helper to reset bridge pipeline

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Message-Id: <20250225-bridge-connector-v4-7-7ecb07b09cad@kernel.org>
Date: Tue, 25 Feb 2025 17:43:55 +0100
From: Maxime Ripard <mripard@...nel.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
 Simona Vetter <simona@...ll.ch>, Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Douglas Anderson <dianders@...omium.org>
Cc: Herve Codina <herve.codina@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Maxime Ripard <mripard@...nel.org>, Simona Vetter <simona.vetter@...ll.ch>
Subject: [PATCH v4 07/15] drm/bridge: Add helper to reset bridge pipeline

Let's provide an helper to make it easier for bridge drivers to
power-cycle their bridge.

Co-developed-by: Simona Vetter <simona.vetter@...ll.ch>
Signed-off-by: Maxime Ripard <mripard@...nel.org>
---
 drivers/gpu/drm/drm_bridge.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_bridge.h     |  2 ++
 2 files changed, 46 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 8241c00e4506eceeb9bb4ba74a38d8f360c65d38..ca894531a2042fc9296c40a1f51a6cdea6e97ed7 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -24,10 +24,11 @@
 #include <linux/err.h>
 #include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 
+#include <drm/drm_atomic_helper.h>
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_debugfs.h>
 #include <drm/drm_edid.h>
 #include <drm/drm_encoder.h>
@@ -1269,10 +1270,53 @@ void drm_bridge_hpd_notify(struct drm_bridge *bridge,
 		bridge->hpd_cb(bridge->hpd_data, status);
 	mutex_unlock(&bridge->hpd_mutex);
 }
 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
 
+/**
+ * drm_bridge_reset_crtc - Reset the pipeline feeding a bridge
+ * @bridge: DRM bridge to reset
+ * @ctx: lock acquisition context
+ *
+ * Reset a @bridge pipeline. It will power-cycle all active components
+ * between the CRTC and connector that bridge is connected to.
+ *
+ * Returns:
+ *
+ * 0 on success or a negative error code on failure. If the error
+ * returned is EDEADLK, the whole atomic sequence must be restarted.
+ */
+int drm_bridge_reset_crtc(struct drm_bridge *bridge,
+			  struct drm_modeset_acquire_ctx *ctx)
+{
+	struct drm_connector *connector;
+	struct drm_encoder *encoder = bridge->encoder;
+	struct drm_device *dev = encoder->dev;
+	struct drm_crtc *crtc;
+	int ret;
+
+	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
+	if (ret)
+		return ret;
+
+	connector = drm_atomic_get_connector_for_encoder(encoder, ctx);
+	if (IS_ERR(connector)) {
+		ret = PTR_ERR(connector);
+		goto out;
+	}
+
+	crtc = connector->state->crtc;
+	ret = drm_atomic_helper_reset_crtc(crtc, ctx);
+	if (ret)
+		goto out;
+
+out:
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
+	return ret;
+}
+EXPORT_SYMBOL(drm_bridge_reset_crtc);
+
 #ifdef CONFIG_OF
 /**
  * of_drm_find_bridge - find the bridge corresponding to the device node in
  *			the global bridge list
  *
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 6fb1da7c195e99143a67a999d16fe361c1e3f4ab..32169e62463bb268a281a5903c0c9f448a1042b3 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1085,10 +1085,12 @@ void drm_bridge_hpd_enable(struct drm_bridge *bridge,
 				      enum drm_connector_status status),
 			   void *data);
 void drm_bridge_hpd_disable(struct drm_bridge *bridge);
 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
 			   enum drm_connector_status status);
+int drm_bridge_reset_crtc(struct drm_bridge *bridge,
+			  struct drm_modeset_acquire_ctx *ctx);
 
 #ifdef CONFIG_DRM_PANEL_BRIDGE
 bool drm_bridge_is_panel(const struct drm_bridge *bridge);
 struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel);
 struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel,

-- 
2.48.1