Commit a25b988f authored Feb 26, 2020 by Laurent Pinchart Committed by Tomi Valkeinen Feb 26, 2020

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 <laurent.pinchart@ideasonboard.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-10-laurent.pinchart@ideasonboard.com

parent 64d05ff7

drivers/gpu/drm/arc/arcpgu_hdmi.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -40,7 +40,7 @@ int arcpgu_drm_hdmi_init(struct drm_device drm, struct device_node np)
		return ret;

		/* Link drm_bridge to encoder */
		ret = drm_bridge_attach(encoder, bridge, NULL);
		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
		if (ret)
		drm_encoder_cleanup(encoder);

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -114,7 +114,7 @@ static int atmel_hlcdc_attach_endpoint(struct drm_device *dev, int endpoint)
		}

		if (bridge) {
		ret = drm_bridge_attach(&output->encoder, bridge, NULL);
		ret = drm_bridge_attach(&output->encoder, bridge, NULL, 0);
		if (!ret)
		return 0;

drivers/gpu/drm/bridge/adv7511/adv7511_drv.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -847,11 +847,17 @@ static void adv7511_bridge_mode_set(struct drm_bridge *bridge,
		adv7511_mode_set(adv, mode, adj_mode);
		}

		static int adv7511_bridge_attach(struct drm_bridge *bridge)
		static int adv7511_bridge_attach(struct drm_bridge *bridge,
		enum drm_bridge_attach_flags flags)
		{
		struct adv7511 *adv = bridge_to_adv7511(bridge);
		int ret;

		if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
		DRM_ERROR("Fix bridge driver to make connector optional!");
		return -EINVAL;
		}

		if (!bridge->encoder) {
		DRM_ERROR("Parent encoder object not found");
		return -ENODEV;

drivers/gpu/drm/bridge/analogix/analogix-anx6345.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -520,11 +520,17 @@ static const struct drm_connector_funcs anx6345_connector_funcs = {
		.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
		};

		static int anx6345_bridge_attach(struct drm_bridge *bridge)
		static int anx6345_bridge_attach(struct drm_bridge *bridge,
		enum drm_bridge_attach_flags flags)
		{
		struct anx6345 *anx6345 = bridge_to_anx6345(bridge);
		int err;

		if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
		DRM_ERROR("Fix bridge driver to make connector optional!");
		return -EINVAL;
		}

		if (!bridge->encoder) {
		DRM_ERROR("Parent encoder object not found");
		return -ENODEV;

drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -886,11 +886,17 @@ static const struct drm_connector_funcs anx78xx_connector_funcs = {
		.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
		};

		static int anx78xx_bridge_attach(struct drm_bridge *bridge)
		static int anx78xx_bridge_attach(struct drm_bridge *bridge,
		enum drm_bridge_attach_flags flags)
		{
		struct anx78xx *anx78xx = bridge_to_anx78xx(bridge);
		int err;

		if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
		DRM_ERROR("Fix bridge driver to make connector optional!");
		return -EINVAL;
		}

		if (!bridge->encoder) {
		DRM_ERROR("Parent encoder object not found");
		return -ENODEV;

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