[PATCH v3 12/21] drm/bridge: Add an ->atomic_check() hook

From: Boris Brezillon <boris.brezillon@collabora.com>
To: dri-devel@lists.freedesktop.org
Cc: Lucas Stach <l.stach@pengutronix.de>,
	Chris Healy <cphealy@gmail.com>,
	Andrey Smirnov <andrew.smirnov@gmail.com>,
	Nikita Yushchenko <nikita.yoush@cogentembedded.com>,
	kernel@collabora.com, Daniel Vetter <daniel@ffwll.ch>,
	Inki Dae <inki.dae@samsung.com>,
	Joonyoung Shim <jy0922.shim@samsung.com>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Rob Clark <robdclark@gmail.com>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org,
	Boris Brezillon <boris.brezillon@collabora.com>
Subject: [PATCH v3 12/21] drm/bridge: Add an ->atomic_check() hook
Date: Wed, 23 Oct 2019 17:45:03 +0200	[thread overview]
Message-ID: <20191023154512.9762-13-boris.brezillon@collabora.com> (raw)
In-Reply-To: <20191023154512.9762-1-boris.brezillon@collabora.com>

So that bridge drivers have a way to check/reject an atomic operation.
The drm_atomic_bridge_chain_check() (which is just a wrapper around
the ->atomic_check() hook) is called in place of
drm_bridge_chain_mode_fixup() (when ->atomic_check() is not implemented,
the core falls back on ->mode_fixup(), so the behavior should stay
the same for existing bridge drivers).

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
---
Changes in v3:
* None

Changes in v2:
* Clarify the fact that ->atomic_check() is replacing ->mode_fixup()
---
 drivers/gpu/drm/drm_atomic_helper.c | 12 +++---
 drivers/gpu/drm/drm_bridge.c        | 62 +++++++++++++++++++++++++++++
 include/drm/drm_bridge.h            | 29 +++++++++++++-
 3 files changed, 96 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index de985ba7ce2d..1d0a19511a0d 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -437,12 +437,12 @@ mode_fixup(struct drm_atomic_state *state)
 		funcs = encoder->helper_private;
 
 		bridge = drm_bridge_chain_get_first_bridge(encoder);
-		ret = drm_bridge_chain_mode_fixup(bridge,
-					&new_crtc_state->mode,
-					&new_crtc_state->adjusted_mode);
-		if (!ret) {
-			DRM_DEBUG_ATOMIC("Bridge fixup failed\n");
-			return -EINVAL;
+		ret = drm_atomic_bridge_chain_check(bridge,
+						    new_crtc_state,
+						    new_conn_state);
+		if (ret) {
+			DRM_DEBUG_ATOMIC("Bridge atomic check failed\n");
+			return ret;
 		}
 
 		if (funcs && funcs->atomic_check) {
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 377866e3214f..990e056296bd 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -615,6 +615,68 @@ void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
 
+static int drm_atomic_bridge_check(struct drm_bridge *bridge,
+				   struct drm_crtc_state *crtc_state,
+				   struct drm_connector_state *conn_state)
+{
+	if (bridge->funcs->atomic_check) {
+		struct drm_bridge_state *bridge_state;
+		int ret;
+
+		bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
+							       bridge);
+		if (WARN_ON(!bridge_state))
+			return -EINVAL;
+
+		ret = bridge->funcs->atomic_check(bridge, bridge_state,
+						  crtc_state, conn_state);
+		if (ret)
+			return ret;
+	} else if (bridge->funcs->mode_fixup) {
+		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
+					       &crtc_state->adjusted_mode))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
+ * @bridge: bridge control structure
+ * @crtc_state: new CRTC state
+ * @conn_state: new connector state
+ *
+ * Calls &drm_bridge_funcs.atomic_check() (falls back on
+ * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
+ * starting from the last bridge to the first. These are called before calling
+ * &drm_encoder_helper_funcs.atomic_check()
+ *
+ * RETURNS:
+ * 0 on success, a negative error code on failure
+ */
+int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
+				  struct drm_crtc_state *crtc_state,
+				  struct drm_connector_state *conn_state)
+{
+	struct drm_encoder *encoder = bridge->encoder;
+	struct drm_bridge *iter;
+
+	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
+		int ret;
+
+		ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
+		if (ret)
+			return ret;
+
+		if (iter == bridge)
+			break;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
+
 /**
  * drm_atomic_helper_bridge_destroy_state() - Default destroy state helper
  * @bridge: the bridge this state refers to
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index b1f557d8dba9..2beb1ef9a733 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -127,7 +127,9 @@ struct drm_bridge_funcs {
 	 * this function passes all other callbacks must succeed for this
 	 * configuration.
 	 *
-	 * The @mode_fixup callback is optional.
+	 * The mode_fixup callback is optional. &drm_bridge_funcs.mode_fixup()
+	 * is not called when &drm_bridge_funcs.atomic_check() is implemented,
+	 * so only one of them should be provided.
 	 *
 	 * NOTE:
 	 *
@@ -391,6 +393,28 @@ struct drm_bridge_funcs {
 	void (*atomic_destroy_state)(struct drm_bridge *bridge,
 				     struct drm_bridge_state *state);
 
+	/**
+	 * @atomic_check:
+	 *
+	 * This method is responsible for checking bridge state correctness.
+	 * It can also check the state of the surrounding components in chain
+	 * to make sure the whole pipeline can work properly.
+	 *
+	 * &drm_bridge_funcs.atomic_check() hooks are called in reverse
+	 * order (from the last to the first bridge).
+	 *
+	 * This method is optional. &drm_bridge_funcs.mode_fixup() is not
+	 * called when &drm_bridge_funcs.atomic_check() is implemented, so only
+	 * one of them should be provided.
+	 *
+	 * RETURNS:
+	 * zero if the check passed, a negative error code otherwise.
+	 */
+	int (*atomic_check)(struct drm_bridge *bridge,
+			    struct drm_bridge_state *bridge_state,
+			    struct drm_crtc_state *crtc_state,
+			    struct drm_connector_state *conn_state);
+
 	/**
 	 * @atomic_reset:
 	 *
@@ -542,6 +566,9 @@ void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
 void drm_bridge_chain_pre_enable(struct drm_bridge *bridge);
 void drm_bridge_chain_enable(struct drm_bridge *bridge);
 
+int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
+				  struct drm_crtc_state *crtc_state,
+				  struct drm_connector_state *conn_state);
 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
 				     struct drm_atomic_state *state);
 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
-- 
2.21.0

