From a25b988ff83f3ca0d8f5acf855fb1717c1c61a69 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Wed, 26 Feb 2020 13:24:29 +0200 Subject: 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: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-10-laurent.pinchart@ideasonboard.com --- drivers/gpu/drm/bridge/tc358768.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/bridge/tc358768.c') diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c index da7af03256f6..1b39e8d37834 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -511,7 +511,8 @@ static const struct mipi_dsi_host_ops tc358768_dsi_host_ops = { .transfer = tc358768_dsi_host_transfer, }; -static int tc358768_bridge_attach(struct drm_bridge *bridge) +static int tc358768_bridge_attach(struct drm_bridge *bridge, + enum drm_bridge_attach_flags flags) { struct tc358768_priv *priv = bridge_to_tc358768(bridge); @@ -520,7 +521,8 @@ static int tc358768_bridge_attach(struct drm_bridge *bridge) return -ENOTSUPP; } - return drm_bridge_attach(bridge->encoder, priv->output.bridge, bridge); + return drm_bridge_attach(bridge->encoder, priv->output.bridge, bridge, + flags); } static enum drm_mode_status -- cgit v1.2.3