| Message ID | 20250206-hotplug-drm-bridge-v6-12-9d6f2c9c3058@bootlin.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add support for hot-pluggable DRM bridges | expand |
On Thu, Feb 06, 2025 at 07:14:27PM +0100, Luca Ceresoli wrote: > In preparation for allowing bridges to be added to and removed from a DRM > card without destroying the whole card, add a new DRM bridge function > called on addition and removal of bridges. > > Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> > > --- > > Changed in v6: > - rebased fixing conflicts > > Changed in v5: > - fixed kerneldoc errors > > This patch was added in v4. > --- > drivers/gpu/drm/drm_bridge.c | 12 ++++++++++++ > include/drm/drm_bridge.h | 23 +++++++++++++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c > index b0834b8644284e5f7751cec81724af849b4180e7..1955a231378050abf1071d74a145831b425c47c5 100644 > --- a/drivers/gpu/drm/drm_bridge.c > +++ b/drivers/gpu/drm/drm_bridge.c > @@ -207,12 +207,18 @@ LIST_HEAD(bridge_list); > */ > void drm_bridge_add(struct drm_bridge *bridge) > { > + struct drm_bridge *br, *tmp; > + > mutex_init(&bridge->hpd_mutex); > > if (bridge->ops & DRM_BRIDGE_OP_HDMI) > bridge->ycbcr_420_allowed = !!(bridge->supported_formats & > BIT(HDMI_COLORSPACE_YUV420)); > > + list_for_each_entry_safe(br, tmp, &bridge_list, list) > + if (br->funcs->bridge_event_notify) > + br->funcs->bridge_event_notify(br, DRM_EVENT_BRIDGE_ADD, bridge); > + > mutex_lock(&bridge_lock); > list_add_tail(&bridge->list, &bridge_list); > mutex_unlock(&bridge_lock); > @@ -249,10 +255,16 @@ EXPORT_SYMBOL(devm_drm_bridge_add); > */ > void drm_bridge_remove(struct drm_bridge *bridge) > { > + struct drm_bridge *br, *tmp; > + > mutex_lock(&bridge_lock); > list_del_init(&bridge->list); > mutex_unlock(&bridge_lock); > > + list_for_each_entry_safe(br, tmp, &bridge_list, list) > + if (br->funcs->bridge_event_notify) > + br->funcs->bridge_event_notify(br, DRM_EVENT_BRIDGE_REMOVE, bridge); > + I think the order should be different: notify about the added bridge after adding to the list, notify about bridge removal before removing it from the list. > mutex_destroy(&bridge->hpd_mutex); > } > EXPORT_SYMBOL(drm_bridge_remove); > diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h > index 1561347c4991dac6022319774510f9560c9283c3..ad7ba444a13e5ecf16f996de3742e4ac67dc21f1 100644 > --- a/include/drm/drm_bridge.h > +++ b/include/drm/drm_bridge.h > @@ -56,6 +56,11 @@ enum drm_bridge_attach_flags { > DRM_BRIDGE_ATTACH_NO_CONNECTOR = BIT(0), > }; > > +enum drm_bridge_event_type { > + DRM_EVENT_BRIDGE_ADD, > + DRM_EVENT_BRIDGE_REMOVE, > +}; > + > /** > * struct drm_bridge_funcs - drm_bridge control functions > */ > @@ -729,6 +734,24 @@ struct drm_bridge_funcs { > struct drm_bridge *bridge, > bool enable, int direction); > > + /** > + * @bridge_event_notify: > + * > + * Notify that another bridge is being added or removed. > + * > + * This callback is optional. Bridges implementing it must always > + * check whether the event refers to a bridge they actually need to > + * interact with. > + * > + * @bridge: bridge being notified > + * @event: event happened (add/remove bridge) > + * @event_bridge: the bridge mentioned by the event (i.e. the > + * bridge being added or removed) > + */ > + void (*bridge_event_notify)(struct drm_bridge *bridge, > + enum drm_bridge_event_type event, > + struct drm_bridge *event_bridge); > + This creates a small issue. It requires drivers to have a bridge, even if they don't need one - e.g. the drm_encoder doesn't get notifications about the added bridges. I'm not sure if that can be solved in an efficient way. > /** > * @debugfs_init: > * > > -- > 2.34.1 >
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index b0834b8644284e5f7751cec81724af849b4180e7..1955a231378050abf1071d74a145831b425c47c5 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -207,12 +207,18 @@ LIST_HEAD(bridge_list); */ void drm_bridge_add(struct drm_bridge *bridge) { + struct drm_bridge *br, *tmp; + mutex_init(&bridge->hpd_mutex); if (bridge->ops & DRM_BRIDGE_OP_HDMI) bridge->ycbcr_420_allowed = !!(bridge->supported_formats & BIT(HDMI_COLORSPACE_YUV420)); + list_for_each_entry_safe(br, tmp, &bridge_list, list) + if (br->funcs->bridge_event_notify) + br->funcs->bridge_event_notify(br, DRM_EVENT_BRIDGE_ADD, bridge); + mutex_lock(&bridge_lock); list_add_tail(&bridge->list, &bridge_list); mutex_unlock(&bridge_lock); @@ -249,10 +255,16 @@ EXPORT_SYMBOL(devm_drm_bridge_add); */ void drm_bridge_remove(struct drm_bridge *bridge) { + struct drm_bridge *br, *tmp; + mutex_lock(&bridge_lock); list_del_init(&bridge->list); mutex_unlock(&bridge_lock); + list_for_each_entry_safe(br, tmp, &bridge_list, list) + if (br->funcs->bridge_event_notify) + br->funcs->bridge_event_notify(br, DRM_EVENT_BRIDGE_REMOVE, bridge); + mutex_destroy(&bridge->hpd_mutex); } EXPORT_SYMBOL(drm_bridge_remove); diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 1561347c4991dac6022319774510f9560c9283c3..ad7ba444a13e5ecf16f996de3742e4ac67dc21f1 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -56,6 +56,11 @@ enum drm_bridge_attach_flags { DRM_BRIDGE_ATTACH_NO_CONNECTOR = BIT(0), }; +enum drm_bridge_event_type { + DRM_EVENT_BRIDGE_ADD, + DRM_EVENT_BRIDGE_REMOVE, +}; + /** * struct drm_bridge_funcs - drm_bridge control functions */ @@ -729,6 +734,24 @@ struct drm_bridge_funcs { struct drm_bridge *bridge, bool enable, int direction); + /** + * @bridge_event_notify: + * + * Notify that another bridge is being added or removed. + * + * This callback is optional. Bridges implementing it must always + * check whether the event refers to a bridge they actually need to + * interact with. + * + * @bridge: bridge being notified + * @event: event happened (add/remove bridge) + * @event_bridge: the bridge mentioned by the event (i.e. the + * bridge being added or removed) + */ + void (*bridge_event_notify)(struct drm_bridge *bridge, + enum drm_bridge_event_type event, + struct drm_bridge *event_bridge); + /** * @debugfs_init: *
In preparation for allowing bridges to be added to and removed from a DRM card without destroying the whole card, add a new DRM bridge function called on addition and removal of bridges. Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> --- Changed in v6: - rebased fixing conflicts Changed in v5: - fixed kerneldoc errors This patch was added in v4. --- drivers/gpu/drm/drm_bridge.c | 12 ++++++++++++ include/drm/drm_bridge.h | 23 +++++++++++++++++++++++ 2 files changed, 35 insertions(+)