Up to now, once a bridge has been attached to a DRM device, it cannot
be undone.
In particular you couldn't rmmod/insmod a DRM driver that uses a bridge,
because the bridge would remain bound to the first (dead) driver instance.
This patch fixes this by introducing drm_encoder_detach() and a ->detach
callback in drm_bridge_funcs for the bridge to be notified about detaches.
It's DRM/KMS driver responsibility to call drm_encoder_detach().
While adding the bridge detach callback, with its kerneldoc, I also added
kerneldoc for attach callback.
Few other kerneldocs fixes around there are included.
Suggested-by: Daniel Vetter <daniel@xxxxxxxx>
Suggested-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Signed-off-by: Andrea Merello <andrea.merello@xxxxxxxxx>
Cc: Archit Taneja <architt@xxxxxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_bridge.c | 29 +++++++++++++++++++++++++++--
include/drm/drm_crtc.h | 26 +++++++++++++++++++++++++-
2 files changed, 52 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 2555430..4840466 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -98,11 +98,11 @@ EXPORT_SYMBOL(drm_bridge_remove);
* @dev: DRM device
* @bridge: bridge control structure
*
- * called by a kms driver to link one of our encoder/bridge to the given
+ * Called by a kms driver to link one of our encoder/bridge to the given
* bridge.
*
* Note that setting up links between the bridge and our encoder/bridge
- * objects needs to be handled by the kms driver itself
+ * objects needs to be handled by the kms driver itself.
*
* RETURNS:
* Zero on success, error code on failure
@@ -125,6 +125,31 @@ int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
EXPORT_SYMBOL(drm_bridge_attach);
/**
+ * drm_bridge_detach - deassociate given bridge from its DRM device
+ *
+ * @bridge: bridge control structure
+ *
+ * Called by a kms driver to unlink the given bridge from its DRM device.
+ *
+ * Note that tearing down links between the bridge and our encoder/bridge
+ * objects needs to be handled by the kms driver itself.
+ */
+void drm_bridge_detach(struct drm_bridge *bridge)
+{
+ if (WARN_ON(!bridge))
+ return;
+
+ if (WARN_ON(!bridge->dev))
+ return;
+
+ if (bridge->funcs->detach)
+ bridge->funcs->detach(bridge);
+
+ bridge->dev = NULL;
+}
+EXPORT_SYMBOL(drm_bridge_detach);
+
+/**
* DOC: bridge callbacks
*
* The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 3fa0275..bb214a1 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1118,12 +1118,33 @@ struct drm_plane {
/**
* struct drm_bridge_funcs - drm_bridge control functions
- * @attach: Called during drm_bridge_attach
*/
struct drm_bridge_funcs {
+ /**
+ * @attach:
+ *
+ * This callback is invoked whenever our bridge is being attached to a
+ * &drm_encoder.
+ *
+ * The attach callback is optional.
+ *
+ * RETURNS:
+ *
+ * Zero on success, error code on failure.
+ */
int (*attach)(struct drm_bridge *bridge);
/**
+ * @detach:
+ *
+ * This callback is invoked whenever our bridge is being detached from a
+ * &drm_encoder.
+ *
+ * The detach callback is optional.
+ */
+ void (*detach)(struct drm_bridge *bridge);
+
+ /**
* @mode_fixup:
*
* This callback is used to validate and adjust a mode. The paramater
@@ -1137,6 +1158,8 @@ struct drm_bridge_funcs {
* this function passes all other callbacks must succeed for this
* configuration.
*
+ * The mode_fixup callback is optional.
+ *
* NOTE:
*
* This function is called in the check phase of atomic modesets, which
@@ -2426,6 +2449,7 @@ extern int drm_bridge_add(struct drm_bridge *bridge);
extern void drm_bridge_remove(struct drm_bridge *bridge);
extern struct drm_bridge *of_drm_find_bridge(struct device_node *np);
extern int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge);
+extern void drm_bridge_detach(struct drm_bridge *bridge);
bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
const struct drm_display_mode *mode,
--
2.7.4
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