To support implementation of DRM connectors on top of DRM bridges instead of by bridges, the drm_bridge needs to expose new operations and data:
- Output detection, hot-plug notification, mode retrieval and EDID retrieval operations - Bitmask of supported operations - Bridge output type - I2C adapter for DDC access
Add and document these.
Three new bridge helper functions are also added to handle hot plug notification in a way that is as transparent as possible for the bridges.
Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Reviewed-by: Boris Brezillon boris.brezillon@collabora.com Reviewed-by: Sam Ravnborg sam@ravnborg.org Tested-by: Sebastian Reichel sebastian.reichel@collabora.com Reviewed-by: Sebastian Reichel sebastian.reichel@collabora.com Acked-by: Daniel Vetter daniel.vetter@ffwll.ch --- drivers/gpu/drm/drm_bridge.c | 201 ++++++++++++++++++++++++++++++++++- include/drm/drm_bridge.h | 192 ++++++++++++++++++++++++++++++++- 2 files changed, 391 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 52dfc67a6cf8..5a8f7d7e05f3 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -95,6 +95,8 @@ static LIST_HEAD(bridge_list); */ void drm_bridge_add(struct drm_bridge *bridge) { + mutex_init(&bridge->hpd_mutex); + mutex_lock(&bridge_lock); list_add_tail(&bridge->list, &bridge_list); mutex_unlock(&bridge_lock); @@ -111,6 +113,8 @@ void drm_bridge_remove(struct drm_bridge *bridge) mutex_lock(&bridge_lock); list_del_init(&bridge->list); mutex_unlock(&bridge_lock); + + mutex_destroy(&bridge->hpd_mutex); } EXPORT_SYMBOL(drm_bridge_remove);
@@ -241,7 +245,7 @@ void drm_bridge_detach(struct drm_bridge *bridge) * Bridge drivers expose operations through the &drm_bridge_funcs structure. * The DRM internals (atomic and CRTC helpers) use the helpers defined in * drm_bridge.c to call bridge operations. Those operations are divided in - * two big categories to support different parts of the bridge usage. + * three big categories to support different parts of the bridge usage. * * - The encoder-related operations support control of the bridges in the * chain, and are roughly counterparts to the &drm_encoder_helper_funcs @@ -271,6 +275,43 @@ void drm_bridge_detach(struct drm_bridge *bridge) * implement them shall thus also implement the atomic version of the * encoder-related operations. This feature is not supported by the legacy * CRTC helpers. + * + * - The connector-related operations support implementing a &drm_connector + * based on a chain of bridges. DRM bridges traditionally create a + * &drm_connector for bridges meant to be used at the end of the chain. This + * puts additional burden on bridge drivers, especially for bridges that may + * be used in the middle of a chain or at the end of it. Furthermore, it + * requires all operations of the &drm_connector to be handled by a single + * bridge, which doesn't always match the hardware architecture. + * + * To simplify bridge drivers and make the connector implementation more + * flexible, a new model allows bridges to unconditionally skip creation of + * &drm_connector and instead expose &drm_bridge_funcs operations to support + * an externally-implemented &drm_connector. Those operations are + * &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes, + * &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify, + * &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When + * implemented, display drivers shall create a &drm_connector instance for + * each chain of bridges, and implement those connector instances based on + * the bridge connector operations. + * + * Bridge drivers shall implement the connector-related operations for all + * the features that the bridge hardware support. For instance, if a bridge + * supports reading EDID, the &drm_bridge_funcs.get_edid shall be + * implemented. This however doesn't mean that the DDC lines are wired to the + * bridge on a particular platform, as they could also be connected to an I2C + * controller of the SoC. Support for the connector-related operations on the + * running platform is reported through the &drm_bridge.ops flags. Bridge + * drivers shall detect which operations they can support on the platform + * (usually this information is provided by ACPI or DT), and set the + * &drm_bridge.ops flags for all supported operations. A flag shall only be + * set if the corresponding &drm_bridge_funcs operation is implemented, but + * an implemented operation doesn't necessarily imply that the corresponding + * flag will be set. Display drivers shall use the &drm_bridge.ops flags to + * decide which bridge to delegate a connector operation to. This mechanism + * allows providing a single static const &drm_bridge_funcs instance in + * bridge drivers, improving security by storing function pointers in + * read-only memory. */
/** @@ -970,6 +1011,164 @@ int drm_atomic_bridge_chain_check(struct drm_bridge *bridge, } EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
+/** + * drm_bridge_detect - check if anything is attached to the bridge output + * @bridge: bridge control structure + * + * If the bridge supports output detection, as reported by the + * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the + * bridge and return the connection status. Otherwise return + * connector_status_unknown. + * + * RETURNS: + * The detection status on success, or connector_status_unknown if the bridge + * doesn't support output detection. + */ +enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge) +{ + if (!(bridge->ops & DRM_BRIDGE_OP_DETECT)) + return connector_status_unknown; + + return bridge->funcs->detect(bridge); +} +EXPORT_SYMBOL_GPL(drm_bridge_detect); + +/** + * drm_bridge_get_modes - fill all modes currently valid for the sink into the + * @connector + * @bridge: bridge control structure + * @connector: the connector to fill with modes + * + * If the bridge supports output modes retrieval, as reported by the + * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to + * fill the connector with all valid modes and return the number of modes + * added. Otherwise return 0. + * + * RETURNS: + * The number of modes added to the connector. + */ +int drm_bridge_get_modes(struct drm_bridge *bridge, + struct drm_connector *connector) +{ + if (!(bridge->ops & DRM_BRIDGE_OP_MODES)) + return 0; + + return bridge->funcs->get_modes(bridge, connector); +} +EXPORT_SYMBOL_GPL(drm_bridge_get_modes); + +/** + * drm_bridge_get_edid - get the EDID data of the connected display + * @bridge: bridge control structure + * @connector: the connector to read EDID for + * + * If the bridge supports output EDID retrieval, as reported by the + * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to + * get the EDID and return it. Otherwise return ERR_PTR(-ENOTSUPP). + * + * RETURNS: + * The retrieved EDID on success, or an error pointer otherwise. + */ +struct edid *drm_bridge_get_edid(struct drm_bridge *bridge, + struct drm_connector *connector) +{ + if (!(bridge->ops & DRM_BRIDGE_OP_EDID)) + return ERR_PTR(-ENOTSUPP); + + return bridge->funcs->get_edid(bridge, connector); +} +EXPORT_SYMBOL_GPL(drm_bridge_get_edid); + +/** + * drm_bridge_hpd_enable - enable hot plug detection for the bridge + * @bridge: bridge control structure + * @cb: hot-plug detection callback + * @data: data to be passed to the hot-plug detection callback + * + * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb + * and @data as hot plug notification callback. From now on the @cb will be + * called with @data when an output status change is detected by the bridge, + * until hot plug notification gets disabled with drm_bridge_hpd_disable(). + * + * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in + * bridge->ops. This function shall not be called when the flag is not set. + * + * Only one hot plug detection callback can be registered at a time, it is an + * error to call this function when hot plug detection is already enabled for + * the bridge. + */ +void drm_bridge_hpd_enable(struct drm_bridge *bridge, + void (*cb)(void *data, + enum drm_connector_status status), + void *data) +{ + if (!(bridge->ops & DRM_BRIDGE_OP_HPD)) + return; + + mutex_lock(&bridge->hpd_mutex); + + if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n")) + goto unlock; + + bridge->hpd_cb = cb; + bridge->hpd_data = data; + + if (bridge->funcs->hpd_enable) + bridge->funcs->hpd_enable(bridge); + +unlock: + mutex_unlock(&bridge->hpd_mutex); +} +EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable); + +/** + * drm_bridge_hpd_disable - disable hot plug detection for the bridge + * @bridge: bridge control structure + * + * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot + * plug detection callback previously registered with drm_bridge_hpd_enable(). + * Once this function returns the callback will not be called by the bridge + * when an output status change occurs. + * + * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in + * bridge->ops. This function shall not be called when the flag is not set. + */ +void drm_bridge_hpd_disable(struct drm_bridge *bridge) +{ + if (!(bridge->ops & DRM_BRIDGE_OP_HPD)) + return; + + mutex_lock(&bridge->hpd_mutex); + if (bridge->funcs->hpd_disable) + bridge->funcs->hpd_disable(bridge); + + bridge->hpd_cb = NULL; + bridge->hpd_data = NULL; + mutex_unlock(&bridge->hpd_mutex); +} +EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable); + +/** + * drm_bridge_hpd_notify - notify hot plug detection events + * @bridge: bridge control structure + * @status: output connection status + * + * Bridge drivers shall call this function to report hot plug events when they + * detect a change in the output status, when hot plug detection has been + * enabled by drm_bridge_hpd_enable(). + * + * This function shall be called in a context that can sleep. + */ +void drm_bridge_hpd_notify(struct drm_bridge *bridge, + enum drm_connector_status status) +{ + mutex_lock(&bridge->hpd_mutex); + if (bridge->hpd_cb) + bridge->hpd_cb(bridge->hpd_data, status); + mutex_unlock(&bridge->hpd_mutex); +} +EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify); + #ifdef CONFIG_OF /** * of_drm_find_bridge - find the bridge corresponding to the device node in diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 38de129d5947..9d5d750973e9 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -23,8 +23,9 @@ #ifndef __DRM_BRIDGE_H__ #define __DRM_BRIDGE_H__
-#include <linux/list.h> #include <linux/ctype.h> +#include <linux/list.h> +#include <linux/mutex.h>
#include <drm/drm_atomic.h> #include <drm/drm_encoder.h> @@ -33,7 +34,10 @@
struct drm_bridge; struct drm_bridge_timings; +struct drm_connector; struct drm_panel; +struct edid; +struct i2c_adapter;
/** * struct drm_bridge_funcs - drm_bridge control functions @@ -497,6 +501,119 @@ struct drm_bridge_funcs { * giving the reason of the failure otherwise. */ struct drm_bridge_state *(*atomic_reset)(struct drm_bridge *bridge); + + /** + * @detect: + * + * Check if anything is attached to the bridge output. + * + * This callback is optional, if not implemented the bridge will be + * considered as always having a component attached to its output. + * Bridges that implement this callback shall set the + * DRM_BRIDGE_OP_DETECT flag in their &drm_bridge->ops. + * + * RETURNS: + * + * drm_connector_status indicating the bridge output status. + */ + enum drm_connector_status (*detect)(struct drm_bridge *bridge); + + /** + * @get_modes: + * + * Fill all modes currently valid for the sink into the &drm_connector + * with drm_mode_probed_add(). + * + * The @get_modes callback is mostly intended to support non-probeable + * displays such as many fixed panels. Bridges that support reading + * EDID shall leave @get_modes unimplemented and implement the + * &drm_bridge_funcs->get_edid callback instead. + * + * This callback is optional. Bridges that implement it shall set the + * DRM_BRIDGE_OP_MODES flag in their &drm_bridge->ops. + * + * The connector parameter shall be used for the sole purpose of + * filling modes, and shall not be stored internally by bridge drivers + * for future usage. + * + * RETURNS: + * + * The number of modes added by calling drm_mode_probed_add(). + */ + int (*get_modes)(struct drm_bridge *bridge, + struct drm_connector *connector); + + /** + * @get_edid: + * + * Read and parse the EDID data of the connected display. + * + * The @get_edid callback is the preferred way of reporting mode + * information for a display connected to the bridge output. Bridges + * that support reading EDID shall implement this callback and leave + * the @get_modes callback unimplemented. + * + * The caller of this operation shall first verify the output + * connection status and refrain from reading EDID from a disconnected + * output. + * + * This callback is optional. Bridges that implement it shall set the + * DRM_BRIDGE_OP_EDID flag in their &drm_bridge->ops. + * + * The connector parameter shall be used for the sole purpose of EDID + * retrieval and parsing, and shall not be stored internally by bridge + * drivers for future usage. + * + * RETURNS: + * + * An edid structure newly allocated with kmalloc() (or similar) on + * success, or NULL otherwise. The caller is responsible for freeing + * the returned edid structure with kfree(). + */ + struct edid *(*get_edid)(struct drm_bridge *bridge, + struct drm_connector *connector); + + /** + * @hpd_notify: + * + * Notify the bridge of hot plug detection. + * + * This callback is optional, it may be implemented by bridges that + * need to be notified of display connection or disconnection for + * internal reasons. One use case is to reset the internal state of CEC + * controllers for HDMI bridges. + */ + void (*hpd_notify)(struct drm_bridge *bridge, + enum drm_connector_status status); + + /** + * @hpd_enable: + * + * Enable hot plug detection. From now on the bridge shall call + * drm_bridge_hpd_notify() each time a change is detected in the output + * connection status, until hot plug detection gets disabled with + * @hpd_disable. + * + * This callback is optional and shall only be implemented by bridges + * that support hot-plug notification without polling. Bridges that + * implement it shall also implement the @hpd_disable callback and set + * the DRM_BRIDGE_OP_HPD flag in their &drm_bridge->ops. + */ + void (*hpd_enable)(struct drm_bridge *bridge); + + /** + * @hpd_disable: + * + * Disable hot plug detection. Once this function returns the bridge + * shall not call drm_bridge_hpd_notify() when a change in the output + * connection status occurs. + * + * This callback is optional and shall only be implemented by bridges + * that support hot-plug notification without polling. Bridges that + * implement it shall also implement the @hpd_enable callback and set + * the DRM_BRIDGE_OP_HPD flag in their &drm_bridge->ops. + */ + void (*hpd_disable)(struct drm_bridge *bridge); };
/** @@ -535,6 +652,39 @@ struct drm_bridge_timings { bool dual_link; };
+/** + * enum drm_bridge_ops - Bitmask of operations supported by the bridge + */ +enum drm_bridge_ops { + /** + * @DRM_BRIDGE_OP_DETECT: The bridge can detect displays connected to + * its output. Bridges that set this flag shall implement the + * &drm_bridge_funcs->detect callback. + */ + DRM_BRIDGE_OP_DETECT = BIT(0), + /** + * @DRM_BRIDGE_OP_EDID: The bridge can retrieve the EDID of the display + * connected to its output. Bridges that set this flag shall implement + * the &drm_bridge_funcs->get_edid callback. + */ + DRM_BRIDGE_OP_EDID = BIT(1), + /** + * @DRM_BRIDGE_OP_HPD: The bridge can detect hot-plug and hot-unplug + * without requiring polling. Bridges that set this flag shall + * implement the &drm_bridge_funcs->hpd_enable and + * &drm_bridge_funcs->hpd_disable callbacks if they support enabling + * and disabling hot-plug detection dynamically. + */ + DRM_BRIDGE_OP_HPD = BIT(2), + /** + * @DRM_BRIDGE_OP_MODES: The bridge can retrieve the modes supported + * by the display at its output. This does not include reading EDID + * which is separately covered by @DRM_BRIDGE_OP_EDID. Bridges that set + * this flag shall implement the &drm_bridge_funcs->get_modes callback. + */ + DRM_BRIDGE_OP_MODES = BIT(3), +}; + /** * struct drm_bridge - central DRM bridge control structure */ @@ -563,6 +713,33 @@ struct drm_bridge { const struct drm_bridge_funcs *funcs; /** @driver_private: pointer to the bridge driver's internal context */ void *driver_private; + /** @ops: bitmask of operations supported by the bridge */ + enum drm_bridge_ops ops; + /** + * @type: Type of the connection at the bridge output + * (DRM_MODE_CONNECTOR_*). For bridges at the end of this chain this + * identifies the type of connected display. + */ + int type; + /** + * @ddc: Associated I2C adapter for DDC access, if any. + */ + struct i2c_adapter *ddc; + /** private: */ + /** + * @hpd_mutex: Protects the @hpd_cb and @hpd_data fields. + */ + struct mutex hpd_mutex; + /** + * @hpd_cb: Hot plug detection callback, registered with + * drm_bridge_hpd_enable(). + */ + void (*hpd_cb)(void *data, enum drm_connector_status status); + /** + * @hpd_data: Private data passed to the Hot plug detection callback + * @hpd_cb. + */ + void *hpd_data; };
static inline struct drm_bridge * @@ -669,6 +846,19 @@ drm_atomic_helper_bridge_propagate_bus_fmt(struct drm_bridge *bridge, u32 output_fmt, unsigned int *num_input_fmts);
+enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge); +int drm_bridge_get_modes(struct drm_bridge *bridge, + struct drm_connector *connector); +struct edid *drm_bridge_get_edid(struct drm_bridge *bridge, + struct drm_connector *connector); +void drm_bridge_hpd_enable(struct drm_bridge *bridge, + void (*cb)(void *data, + 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); + #ifdef CONFIG_DRM_PANEL_BRIDGE struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel); struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel,