Hi Mihail,
On Wed, Dec 11, 2019 at 11:01:37AM +0000, Mihail Atanassov wrote:
> On Tuesday, 10 December 2019 22:57:04 GMT Laurent Pinchart wrote:
> > 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@xxxxxxxxxxxxxxxx>
> > Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> > ---
> > Changes since v2:
> >
> > - Add wrappers around the .detect(), .get_modes() and .get_edid()
> > operations
> > - Warn bridge drivers about valid usage of the connector argument to
> > .get_modes() and .get_edid()
> >
> > Changes since v1:
> >
> > - Make .hpd_enable() and .hpd_disable() optional
> > - Rename .lost_hotplug() to .hpd_notify()
> > - Add ddc field to drm_bridge
> > ---
> > drivers/gpu/drm/drm_bridge.c | 162 +++++++++++++++++++++++++++++
> > include/drm/drm_bridge.h | 193 ++++++++++++++++++++++++++++++++++-
> > 2 files changed, 354 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> > index c2cf0c90fa26..473353bd762f 100644
> > --- a/drivers/gpu/drm/drm_bridge.c
> > +++ b/drivers/gpu/drm/drm_bridge.c
> > @@ -70,6 +70,8 @@ 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);
> > @@ -86,6 +88,8 @@ 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);
> >
> > @@ -516,6 +520,164 @@ void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
> > }
> > EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
> >
> > +/**
> > + * 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 || !(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)
>
> Is this check necessary given the DRM_BRIDGE_OP_HPD check? Would a
>
> if (WARN_ON(!bridge->funcs->hpd_enable))
> return;
>
> suffice? Similarly for the check in _disable below.
You're right. I'll do so and move it out of the hpd_mutex-protected
section.
> > + 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 || !(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 694e153a7531..56ac260094f4 100644
> > --- a/include/drm/drm_bridge.h
> > +++ b/include/drm/drm_bridge.h
> > @@ -23,15 +23,20 @@
> > #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_encoder.h>
> > #include <drm/drm_mode_object.h>
> > #include <drm/drm_modes.h>
> >
> > 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
> > @@ -338,6 +343,119 @@ struct drm_bridge_funcs {
> > */
> > void (*atomic_post_disable)(struct drm_bridge *bridge,
> > struct drm_atomic_state *old_state);
> > +
> > + /**
> > + * @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-probable
> > + * 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 readind 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);
> > };
> >
> > /**
> > @@ -376,6 +494,39 @@ 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 retrieving the modes supported
>
> s/retrieving/retrieve/
>
> > + * by the display at its output. This does not include readind EDID
>
> s/readind/reading/. I saw the same typo somewhere above too, so please apply
> to the whole file.
>
> > + * 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
> > */
> > @@ -402,6 +553,33 @@ 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;
> > };
> >
> > void drm_bridge_add(struct drm_bridge *bridge);
> > @@ -491,6 +669,19 @@ void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
> > void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
> > struct drm_atomic_state *state);
> >
> > +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,
--
Regards,
Laurent Pinchart
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