This series makes every drm_panel create a drm_panel_bridge wrapping it, as
previously discussed [1][2].
A panel_bridge is currently created only afterwards by the component
accessing it (such as the previous bridge), but that creates a mismatch
between the panel and the panel_bridge lifetimes and devm ownership.
== Series outline
1. The most common pattern for panel_bridge creation is:
| drm_of_find_panel_or_bridge(..., &panel, &bridge);
| if (panel)
| bridge = drm_panel_bridge_add();
Adapt drm_of_find_panel_or_bridge() so it prioritizes the bridge, not
the panel. With this small change all drivers using the above pattern
get ready in advance for when every panel will have a bridge
(a few commits below).
drm: of: drm_of_find_panel_or_bridge: simplify freeing the remote node
pointer
drm: of: drm_of_find_panel_or_bridge: simplify error return paths
drm: of: drm_of_find_panel_or_bridge: prioritize the bridge, not the panel
2. Address circular module dependency that would arise in the following
commit [RFC!]
drm/panel: merge the drm_kms_helper module into the drm module
3. The main commit
drm/bridge: panel: add a panel_bridge to every panel
4. After the previous commit, many drivers not using the pattern in (1.)
will unconditionally create a second panel_bridge for the same panel.
Being an RFC, fix *some* of them as an example; if the approach will
be acked, all of them will be converted in a later iteration.
drm/bridge: tc358767: don't create a panel_bridge
drm/bridge: waveshare-dsi: don't create a panel_bridge
drm/mcde: dsi: simplify device_node management using scoped for_each
variant
drm/mcde: dsi: don't create a panel_bridge
drm/bridge: fsl-ldb: don't create a panel_bridge
drm/bridge: samsung-dsim: don't create a panel_bridge
== Grand plan
This is part of the work to support hotplug of DRM bridges. The grand plan
was discussed in [0].
Here's the work breakdown (➜ marks the current series):
1. ➜ add refcounting to DRM bridges struct drm_bridge,
based on devm_drm_bridge_alloc()
A. ✔ add new alloc API and refcounting (v6.16)
B. ✔ convert all bridge drivers to new API (v6.17)
C. ✔ kunit tests (v6.17)
D. ✔ add get/put to drm_bridge_add/remove() + attach/detach()
and warn on old allocation pattern (v6.17)
E. ➜ add get/put on drm_bridge accessors
1. ✔ drm_bridge_chain_get_first_bridge(), add cleanup action (v6.18)
2. ✔ drm_bridge_get_prev_bridge() (v6.18)
3. ✔ drm_bridge_get_next_bridge() (v6.19)
4. ✔ drm_for_each_bridge_in_chain() (v6.19)
5. ✔ drm_bridge_connector_init (v6.19)
6. ✔ protect encoder bridge chain with a mutex (v7.2)
7. ✔ of_drm_find_bridge
a. ✔ add of_drm_get_bridge() (v7.0),
convert basic direct users (v7.0-v7.1)
b. ✔ convert direct of_drm_get_bridge() users, part 2 (v7.0)
c. ✔ convert direct of_drm_get_bridge() users, part 3 (v7.0)
d. ✔ convert direct of_drm_get_bridge() users, part 4 (v7.1-v7.2)
e. ✔ bridge-only drm_of_find_panel_or_bridge() users (v7.2)
8. ➜ panel_bridge lifetime
a. … cleanup DRM_PANEL in bridge drivers
b. ➜ add a panel_bridge to every panel
9. ✔ enforce drm_bridge_add before drm_bridge_attach (v6.19)
F. ✔ debugfs improvements
1. ✔ add top-level 'bridges' file (v6.16)
2. ✔ show refcount and list lingering bridges (v6.19)
2. ✔ handle gracefully atomic updates during bridge removal
A. ✔ Add drm_bridge_enter/exit() to protect device resources (v7.0)
B. ✔ Add drm_bridge_clear_and_put() (v7.1)
3. … DSI host-device driver interaction
4. ✔ removing the need for the "always-disconnected" connector
5. ✔ Migrate i.MX LCDIF driver to bridge-connector (v7.2)
6. … DRM bridge hotplug
A. … Bridge hotplug management in the DRM core
1. ✔ bridge-connector: attach encoder to the connector (v7.2)
2. … drm bridge hotplug
B. Device tree description
[0]
https://lore.kernel.org/lkml/[email protected]/#t
[1]
https://lore.kernel.org/all/emuj2innmp6zmzd7pyakqzjqpdzhly6qfhakya3ydwmd63pl26@5jwxaidpikjw/
[2]
https://lore.kernel.org/lkml/[email protected]/
Signed-off-by: Luca Ceresoli <[email protected]>
---
Luca Ceresoli (11):
drm: of: drm_of_find_panel_or_bridge: simplify freeing the remote node
pointer
drm: of: drm_of_find_panel_or_bridge: simplify error return paths
drm: of: drm_of_find_panel_or_bridge: prioritize the bridge, not the panel
drm/panel: merge the drm_kms_helper module into the drm module
drm/bridge: panel: add a panel_bridge to every panel
drm/bridge: tc358767: don't create a panel_bridge
drm/bridge: waveshare-dsi: don't create a panel_bridge
drm/mcde: dsi: simplify device_node management using scoped for_each
variant
drm/mcde: dsi: don't create a panel_bridge
drm/bridge: fsl-ldb: don't create a panel_bridge
drm/bridge: samsung-dsim: don't create a panel_bridge
drivers/gpu/drm/Makefile | 7 +++--
drivers/gpu/drm/bridge/fsl-ldb.c | 18 ++++---------
drivers/gpu/drm/bridge/panel.c | 47 +++++++++++++++++-----------------
drivers/gpu/drm/bridge/samsung-dsim.c | 19 +++-----------
drivers/gpu/drm/bridge/tc358767.c | 22 +++++-----------
drivers/gpu/drm/bridge/waveshare-dsi.c | 16 ++++--------
drivers/gpu/drm/drm_of.c | 36 ++++++++++++--------------
drivers/gpu/drm/drm_panel.c | 3 +++
drivers/gpu/drm/mcde/mcde_dsi.c | 47 ++++++++--------------------------
include/drm/drm_panel.h | 8 ++++++
10 files changed, 83 insertions(+), 140 deletions(-)
---
base-commit: c0f5782834718a69465a7169112062d4412856e4
change-id: 20260812-drm-bridge-every-panel-a1596d6efea4
Best regards,
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
