linux-toradex.git/drivers/gpu/drm/bridge/panel.c, branch v5.19-rc3

drm: bridge: panel: Register connector if DRM device is already registered

2022-04-19T16:11:27+00:00

If panel_bridge_attach() happens after DRM device registration, the
created connector will not be registered by the DRM core anymore. Fix
this by registering it explicitly in such case.

This fixes the following issue observed on Samsung Exynos4210-based Trats
board with a DSI panel (the panel driver is registered after the Exynos DRM
component device is bound):

$ ./modetest -c -Mexynos
could not get connector 56: No such file or directory
Segmentation fault

While touching this, move the connector reset() call also under the DRM
device registered check, because otherwise it is not really needed.

Fixes: 934aef885f9d ("drm: bridge: panel: Reset the connector state pointer")
Signed-off-by: Marek Szyprowski 
Reviewed-by: Jagan Teki 
Signed-off-by: Robert Foss 
Link: https://patchwork.freedesktop.org/patch/msgid/20220419091422.4255-1-m.szyprowski@samsung.com

drm: bridge: panel: Reset the connector state pointer

2022-03-31T14:21:31+00:00

Trigger hotplug event with drm_kms_helper_hotplug_event might fail if the
connector state pointer is NULL.

BUG observed in exynos dsi driver where drm_bridge_attach is trying to
register a connector in panel_bridge before the hotplug event is triggered.

WARNING: CPU: 1 PID: 1 at drivers/gpu/drm/drm_atomic_state_helper.c:494 drm_atomic_helper_connector_duplicate_state+0x94/0x9c
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 5.16.0-rc1-00009-g704b1dbfa4c2 #11058
Hardware name: Samsung Exynos (Flattened Device Tree)
[] (unwind_backtrace) from [] (show_stack+0x10/0x14)
[] (show_stack) from [] (dump_stack_lvl+0x58/0x70)
[] (dump_stack_lvl) from [] (__warn+0xd0/0x134)
[] (__warn) from [] (warn_slowpath_fmt+0x5c/0xb4)
[] (warn_slowpath_fmt) from [] (drm_atomic_helper_connector_duplicate_state+0x94/0x9c)
[] (drm_atomic_helper_connector_duplicate_state) from [] (drm_atomic_get_connector_state+0xd4/0x190)
[] (drm_atomic_get_connector_state) from [] (__drm_atomic_helper_set_config+0x314/0x368)
[] (__drm_atomic_helper_set_config) from [] (drm_client_modeset_commit_atomic+0x170/0x278)
[] (drm_client_modeset_commit_atomic) from [] (drm_client_modeset_commit_locked+0x60/0x1c8)
[] (drm_client_modeset_commit_locked) from [] (drm_client_modeset_commit+0x24/0x40)
[] (drm_client_modeset_commit) from [] (drm_fb_helper_set_par+0xb8/0xf8)
[] (drm_fb_helper_set_par) from [] (fbcon_init+0x2c0/0x518)
[] (fbcon_init) from [] (visual_init+0xc0/0x108)
[] (visual_init) from [] (do_bind_con_driver+0x1b8/0x3a4)
[] (do_bind_con_driver) from [] (do_take_over_console+0x13c/0x1e8)
[] (do_take_over_console) from [] (do_fbcon_takeover+0x78/0xd8)
[] (do_fbcon_takeover) from [] (register_framebuffer+0x208/0x2e0)
[] (register_framebuffer) from [] (__drm_fb_helper_initial_config_and_unlock+0x400/0x63c)
[] (__drm_fb_helper_initial_config_and_unlock) from [] (drm_kms_helper_hotplug_event+0x24/0x30)
[] (drm_kms_helper_hotplug_event) from [] (exynos_dsi_host_attach+0x174/0x1fc)
[] (exynos_dsi_host_attach) from [] (s6e8aa0_probe+0x1b4/0x218)

So reset the atomic state for a given connector by freeing the state pointer
and allocate a new empty state object. This can be done using connector
funcs->reset helper and has to be done before the hotplug even calls.

This patch calls the connector->funcs->reset in panel_bridge_attach.

Signed-off-by: Jagan Teki 
Acked-by: Marek Szyprowski 
Tested-by: Marek Szyprowski 
Signed-off-by: Robert Foss 
Link: https://patchwork.freedesktop.org/patch/msgid/20220303163654.3381470-3-jagan@amarulasolutions.com

drm: Plumb debugfs_init through to panels

2022-02-15T23:25:18+00:00

We'd like panels to be able to add things to debugfs underneath the
connector's directory. Let's plumb it through. A panel will be able to
put things in a "panel" directory under the connector's
directory. Note that debugfs is not ABI and so it's always possible
that the location that the panel gets for its debugfs could change in
the future.

NOTE: this currently only works if you're using a modern
architecture. Specifically the plumbing relies on _both_
drm_bridge_connector and drm_panel_bridge. If you're not using one or
both of these things then things won't be plumbed through.

As a side effect of this change, drm_bridges can also get callbacks to
put stuff underneath the connector's debugfs directory. At the moment
all bridges in the chain have their debugfs_init() called with the
connector's root directory.

Signed-off-by: Douglas Anderson 
Reviewed-by: Javier Martinez Canillas 
Reviewed-by: Laurent Pinchart 
Link: https://patchwork.freedesktop.org/patch/msgid/20220204161245.v2.2.Ib0bd5346135cbb0b63006b69b61d4c8af6484740@changeid

drm/bridge: Move devm_drm_of_get_bridge to bridge/panel.c

2021-09-22T08:44:00+00:00

By depending on devm_drm_panel_bridge_add(), devm_drm_of_get_bridge()
introduces a circular dependency between the modules drm (where
devm_drm_of_get_bridge() ends up) and drm_kms_helper (where
devm_drm_panel_bridge_add() is).

Fix this by moving devm_drm_of_get_bridge() to bridge/panel.c and thus
drm_kms_helper.

Fixes: 87ea95808d53 ("drm/bridge: Add a function to abstract away panels")
Reported-by: Stephen Rothwell 
Signed-off-by: Maxime Ripard 
Tested-by: Heiko Stuebner 
Acked-by: Thomas Zimmermann 
Link: https://patchwork.freedesktop.org/patch/msgid/20210917180925.2602266-1-maxime@cerno.tech

drm: bridge/panel: Cleanup connector on bridge detach

2021-03-29T15:46:01+00:00

If we don't call drm_connector_cleanup() manually in
panel_bridge_detach(), the connector will be cleaned up with the other
DRM objects in the call to drm_mode_config_cleanup(). However, since our
drm_connector is devm-allocated, by the time drm_mode_config_cleanup()
will be called, our connector will be long gone. Therefore, the
connector must be cleaned up when the bridge is detached to avoid
use-after-free conditions.

v2: Cleanup connector only if it was created

v3: Add FIXME

v4: (Use connector->dev) directly in if() block

Fixes: 13dfc0540a57 ("drm/bridge: Refactor out the panel wrapper from the lvds-encoder bridge.")
Cc:  # 4.12+
Cc: Andrzej Hajda 
Cc: Neil Armstrong 
Cc: Laurent Pinchart 
Cc: Jonas Karlman 
Cc: Jernej Skrabec 
Signed-off-by: Paul Cercueil 
Reviewed-by: Laurent Pinchart 
Link: https://patchwork.freedesktop.org/patch/msgid/20210327115742.18986-2-paul@crapouillou.net

drm: Remove unnecessary drm_panel_attach and drm_panel_detach

2020-08-08T07:06:33+00:00

These functions are now empty and no longer
useful so remove the functions and their uses.

Signed-off-by: Joe Perches 
Cc: Bernard Zhao 
Cc: Maarten Lankhorst 
Cc: Maxime Ripard ,
Cc: Thomas Zimmermann 
Cc: Thierry Reding 
Cc: David Airlie 
Cc: Daniel Vetter 
Cc: Linus Walleij 
Cc: Icenowy Zheng ,
Cc: Jagan Teki 
Cc: Laurent Pinchart 
Cc: Robert Chiras 
Cc: dri-devel@lists.freedesktop.org,
Cc: linux-kernel@vger.kernel.org
Cc: opensource.kernel@vivo.com
Signed-off-by: Sam Ravnborg  # Fixed build and a few warnings
Link: https://patchwork.freedesktop.org/patch/msgid/9e13761020750b1ce2f1fabee23ef6e2a2942882.camel@perches.com

drm/bridge: panel: Return always an error pointer in drm_panel_bridge_add()

2020-04-25T14:48:55+00:00

Since commit 89958b7cd955 ("drm/bridge: panel: Infer connector type from
panel by default"), drm_panel_bridge_add() and their variants can return
NULL and an error pointer. This is fine but none of the actual users of
the API are checking for the NULL value. Instead of change all the
users, seems reasonable to return an error pointer instead. So change
the returned value for those functions when the connector type is unknown.

Suggested-by: Laurent Pinchart 
Signed-off-by: Enric Balletbo i Serra 
Reviewed-by: Laurent Pinchart 
Signed-off-by: Sam Ravnborg 
Link: https://patchwork.freedesktop.org/patch/msgid/20200416210654.2468805-1-enric.balletbo@collabora.com

drm/bridge: fix kernel-doc warning in panel.c

2020-04-05T20:23:10+00:00

Add missing documentation to fix following warning:
panel.c:303: warning: Function parameter or member 'bridge' not described in 'drm_panel_bridge_connector'

Signed-off-by: Sam Ravnborg 
Reviewed-by: Daniel Vetter 
Cc: Laurent Pinchart 
Cc: Boris Brezillon 
Cc: Mihail Atanassov 
Cc: Andrzej Hajda 
Cc: Neil Armstrong 
Cc: Jonas Karlman 
Cc: Jernej Skrabec 
Link: https://patchwork.freedesktop.org/patch/msgid/20200328132025.19910-7-sam@ravnborg.org

drm/bridge: panel: Implement bridge connector operations

2020-02-26T11:31:39+00:00

Implement the newly added bridge connector operations, allowing the
usage of drm_bridge_panel with drm_bridge_connector.

Signed-off-by: Laurent Pinchart 
Reviewed-by: Boris Brezillon 
Reviewed-by: Sam Ravnborg 
Tested-by: Sebastian Reichel 
Reviewed-by: Sebastian Reichel 
Signed-off-by: Tomi Valkeinen 
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-18-laurent.pinchart@ideasonboard.com

drm/bridge: Extend bridge API to disable connector creation

2020-02-26T11:31:23+00:00

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