[PATCH RFC 02/19] drm: Support custom encoder/bridge enable/disable sequences officially

[Boris Brezillon]

The VC4 and Exynos DSI encoder drivers need a custom enable/disable
sequence and manually set encoder->bridge to NULL to prevent the core
from calling the bridge hooks.

Let's provide a more official way to support custom bridge/encoder
enable/disable sequences.

Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 13 +++++++---
 drivers/gpu/drm/drm_crtc_helper.c   | 38 ++++++++++++++++++-----------
 include/drm/drm_encoder.h           |  9 +++++++
 3 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 4706439fb490..15ea61877122 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1030,7 +1030,8 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 		 * Each encoder has at most one connector (since we always steal
 		 * it away), so we won't call disable hooks twice.
 		 */
-		drm_atomic_bridge_disable(encoder->bridge, old_state);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_atomic_bridge_disable(encoder->bridge, old_state);
 
 		/* Right function depends upon target state. */
 		if (funcs) {
@@ -1044,7 +1045,9 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
 				funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
 		}
 
-		drm_atomic_bridge_post_disable(encoder->bridge, old_state);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_atomic_bridge_post_disable(encoder->bridge,
+						       old_state);
 	}
 
 	for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
@@ -1342,7 +1345,8 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
 		 * Each encoder has at most one connector (since we always steal
 		 * it away), so we won't call enable hooks twice.
 		 */
-		drm_atomic_bridge_pre_enable(encoder->bridge, old_state);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_atomic_bridge_pre_enable(encoder->bridge, old_state);
 
 		if (funcs) {
 			if (funcs->atomic_enable)
@@ -1353,7 +1357,8 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
 				funcs->commit(encoder);
 		}
 
-		drm_atomic_bridge_enable(encoder->bridge, old_state);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_atomic_bridge_enable(encoder->bridge, old_state);
 	}
 
 	drm_atomic_helper_commit_writebacks(dev, old_state);
diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index fa3694836c22..87dae37fec12 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -160,14 +160,16 @@ drm_encoder_disable(struct drm_encoder *encoder)
 	if (!encoder_funcs)
 		return;
 
-	drm_bridge_disable(encoder->bridge);
+	if (!encoder->custom_bridge_enable_disable_seq)
+		drm_bridge_disable(encoder->bridge);
 
 	if (encoder_funcs->disable)
 		(*encoder_funcs->disable)(encoder);
 	else if (encoder_funcs->dpms)
 		(*encoder_funcs->dpms)(encoder, DRM_MODE_DPMS_OFF);
 
-	drm_bridge_post_disable(encoder->bridge);
+	if (!encoder->custom_bridge_enable_disable_seq)
+		drm_bridge_post_disable(encoder->bridge);
 }
 
 static void __drm_helper_disable_unused_functions(struct drm_device *dev)
@@ -365,13 +367,15 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 		if (!encoder_funcs)
 			continue;
 
-		drm_bridge_disable(encoder->bridge);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_bridge_disable(encoder->bridge);
 
 		/* Disable the encoders as the first thing we do. */
 		if (encoder_funcs->prepare)
 			encoder_funcs->prepare(encoder);
 
-		drm_bridge_post_disable(encoder->bridge);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_bridge_post_disable(encoder->bridge);
 	}
 
 	drm_crtc_prepare_encoders(dev);
@@ -414,12 +418,14 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 		if (!encoder_funcs)
 			continue;
 
-		drm_bridge_pre_enable(encoder->bridge);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_bridge_pre_enable(encoder->bridge);
 
 		if (encoder_funcs->commit)
 			encoder_funcs->commit(encoder);
 
-		drm_bridge_enable(encoder->bridge);
+		if (!encoder->custom_bridge_enable_disable_seq)
+			drm_bridge_enable(encoder->bridge);
 	}
 
 	/* Calculate and store various constants which
@@ -825,18 +831,22 @@ static void drm_helper_encoder_dpms(struct drm_encoder *encoder, int mode)
 	if (!encoder_funcs)
 		return;
 
-	if (mode == DRM_MODE_DPMS_ON)
-		drm_bridge_pre_enable(bridge);
-	else
-		drm_bridge_disable(bridge);
+	if (!encoder->custom_bridge_enable_disable_seq) {
+		if (mode == DRM_MODE_DPMS_ON)
+			drm_bridge_pre_enable(bridge);
+		else
+			drm_bridge_disable(bridge);
+	}
 
 	if (encoder_funcs->dpms)
 		encoder_funcs->dpms(encoder, mode);
 
-	if (mode == DRM_MODE_DPMS_ON)
-		drm_bridge_enable(bridge);
-	else
-		drm_bridge_post_disable(bridge);
+	if (!encoder->custom_bridge_enable_disable_seq) {
+		if (mode == DRM_MODE_DPMS_ON)
+			drm_bridge_enable(bridge);
+		else
+			drm_bridge_post_disable(bridge);
+	}
 }
 
 static int drm_helper_choose_crtc_dpms(struct drm_crtc *crtc)
diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h
index 70cfca03d812..d986ff1197ce 100644
--- a/include/drm/drm_encoder.h
+++ b/include/drm/drm_encoder.h
@@ -175,6 +175,15 @@ struct drm_encoder {
 	struct drm_bridge *bridge;
 	const struct drm_encoder_funcs *funcs;
 	const struct drm_encoder_helper_funcs *helper_private;
+
+	/**
+	 * @custom_bridge_enable_disable_seq: Set to true if the encoder needs
+	 * a custom bridge/encoder enable/disable sequence. In that case the
+	 * driver is responsible for calling the
+	 * drm[_atomic]_bridge_{pre_enable,enable,disable,post_disable}()
+	 * functions as part of its encoder enable/disable handling.
+	 */
+	uint32_t custom_bridge_enable_disable_seq : 1;
 };
 
 #define obj_to_encoder(x) container_of(x, struct drm_encoder, base)
-- 
2.21.0