path: root/drivers/gpu/drm/msm/dsi
diff options
authorLaurent Pinchart <>2020-02-26 13:24:29 +0200
committerTomi Valkeinen <>2020-02-26 13:31:23 +0200
commita25b988ff83f3ca0d8f5acf855fb1717c1c61a69 (patch)
tree9d6b35a263aaa6b03ac6db912cbe1ab528faadde /drivers/gpu/drm/msm/dsi
parent64d05ff758e39b7c908b96f5e19a5e519092eac8 (diff)
drm/bridge: Extend bridge API to disable connector creation
Most bridge drivers create a DRM connector to model the connector at the output of the bridge. This model is historical and has worked pretty well so far, but causes several issues: - It prevents supporting more complex display pipelines where DRM connector operations are split over multiple components. For instance a pipeline with a bridge connected to the DDC signals to read EDID data, and another one connected to the HPD signal to detect connection and disconnection, will not be possible to support through this model. - It requires every bridge driver to implement similar connector handling code, resulting in code duplication. - It assumes that a bridge will either be wired to a connector or to another bridge, but doesn't support bridges that can be used in both positions very well (although there is some ad-hoc support for this in the analogix_dp bridge driver). In order to solve these issues, ownership of the connector should be moved to the display controller driver (where it can be implemented using helpers provided by the core). Extend the bridge API to allow disabling connector creation in bridge drivers as a first step towards the new model. The new flags argument to the bridge .attach() operation allows instructing the bridge driver to skip creating a connector. Unconditionally set the new flags argument to 0 for now to keep the existing behaviour, and modify all existing bridge drivers to return an error when connector creation is not requested as they don't support this feature yet. The change is based on the following semantic patch, with manual review and edits. @ rule1 @ identifier funcs; identifier fn; @@ struct drm_bridge_funcs funcs = { ..., .attach = fn }; @ depends on rule1 @ identifier rule1.fn; identifier bridge; statement S, S1; @@ int fn( struct drm_bridge *bridge + , enum drm_bridge_attach_flags flags ) { ... when != S + if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) { + DRM_ERROR("Fix bridge driver to make connector optional!"); + return -EINVAL; + } + S1 ... } @ depends on rule1 @ identifier rule1.fn; identifier bridge, flags; expression E1, E2, E3; @@ int fn( struct drm_bridge *bridge, enum drm_bridge_attach_flags flags ) { <... drm_bridge_attach(E1, E2, E3 + , flags ) ...> } @@ expression E1, E2, E3; @@ drm_bridge_attach(E1, E2, E3 + , 0 ) Signed-off-by: Laurent Pinchart <> Reviewed-by: Boris Brezillon <> Acked-by: Sam Ravnborg <> Reviewed-by: Tomi Valkeinen <> Tested-by: Sebastian Reichel <> Reviewed-by: Sebastian Reichel <> Acked-by: Daniel Vetter <> Signed-off-by: Tomi Valkeinen <> Link:
Diffstat (limited to 'drivers/gpu/drm/msm/dsi')
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpu/drm/msm/dsi/dsi_manager.c b/drivers/gpu/drm/msm/dsi/dsi_manager.c
index 104115d112eb..6af26ab5b09d 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_manager.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_manager.c
@@ -684,7 +684,7 @@ struct drm_bridge *msm_dsi_manager_bridge_init(u8 id)
bridge = &dsi_bridge->base;
bridge->funcs = &dsi_mgr_bridge_funcs;
- ret = drm_bridge_attach(encoder, bridge, NULL);
+ ret = drm_bridge_attach(encoder, bridge, NULL, 0);
if (ret)
goto fail;
@@ -713,7 +713,7 @@ struct drm_connector *msm_dsi_manager_ext_bridge_init(u8 id)
encoder = msm_dsi->encoder;
/* link the internal dsi bridge to the external bridge */
- drm_bridge_attach(encoder, ext_bridge, int_bridge);
+ drm_bridge_attach(encoder, ext_bridge, int_bridge, 0);
* we need the drm_connector created by the external bridge