drm/bridge: Add connector-related bridge operations and data

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>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-8-laurent.pinchart@ideasonboard.com
This commit is contained in:
Laurent Pinchart 2020-02-26 13:24:27 +02:00 committed by Tomi Valkeinen
parent 0451369bc5
commit 11f6c4b1b2
2 changed files with 391 additions and 2 deletions

View File

@ -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

View File

@ -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,