kernel/linux.git/drivers/gpu/drm/drm_bridge.c, branch v5.19

drm/bridge: Document the probe issue with MIPI-DSI bridges

2021-09-24T17:25:23+00:00

Interactions between bridges, panels, MIPI-DSI host and the component framework are not trivial and can lead to probing issues when implementing a display driver. Let's document the various cases we need too consider, and the solution to support all the cases. Signed-off-by: Maxime Ripard Reviewed-by: Andrzej Hajda Link: https://patchwork.freedesktop.org/patch/msgid/20210910101218.1632297-3-maxime@cerno.tech

drm/bridge: Add documentation sections

2021-09-24T17:25:16+00:00

The bridge documentation overview is quite packed already, and we'll add some more documentation that isn't part of an overview at all. Let's add some sections to the documentation to separate each bits. Reviewed-by: Andrzej Hajda Reviewed-by: Sam Ravnborg Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20210910101218.1632297-2-maxime@cerno.tech

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: Add a function to abstract away panels

2021-09-14T08:39:01+00:00

Display drivers so far need to have a lot of boilerplate to first retrieve either the panel or bridge that they are connected to using drm_of_find_panel_or_bridge(), and then either deal with each with ad-hoc functions or create a drm panel bridge through drm_panel_bridge_add. In order to reduce the boilerplate and hopefully create a path of least resistance towards using the DRM panel bridge layer, let's create the function devm_drm_of_get_bridge() to reduce that boilerplate. Signed-off-by: Maxime Ripard Reviewed-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20210910130941.1740182-2-maxime@cerno.tech

drm: Fix typo in comments

2021-08-02T08:19:43+00:00

fix typo for drm v1->v2: respin with the change "iff ==> implies that" Signed-off-by: Cai Huoqing Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210730132729.376-1-caihuoqing@baidu.com

drm/bridge: Centralize error message when bridge attach fails

2021-07-28T13:33:12+00:00

Being informed of a failure to attach a bridge is useful, and many drivers prints an error message in that case. Move the message to drm_bridge_attach() to avoid code duplication. Suggested-by: Stephen Boyd Signed-off-by: Laurent Pinchart Reviewed-by: Tomi Valkeinen Reviewed-by: Jyri Sarha

drm/bridge: Fix the stop condition of drm_bridge_chain_pre_enable()

2021-04-20T15:56:44+00:00

The drm_bridge_chain_pre_enable() is not the proper opposite of drm_bridge_chain_post_disable(). It continues along the chain to _before_ the starting bridge. Let's fix that. Fixes: 05193dc38197 ("drm/bridge: Make the bridge chain a double-linked list") Signed-off-by: Douglas Anderson Reviewed-by: Andrzej Hajda Reviewed-by: Laurent Pinchart Link: https://patchwork.freedesktop.org/patch/msgid/20210416153909.v4.1.If62a003f76a2bc4ccc6c53565becc05d2aad4430@changeid

drm: bridge: Pass drm_display_info to drm_bridge_funcs .mode_valid()

2020-06-23T17:53:27+00:00

When validating a mode, bridges may need to do so in the context of a display, as specified by drm_display_info. An example is the meson dw-hdmi bridge that needs to consider the YUV 4:2:0 output format to perform clock calculations. Bridges that need the display info currently retrieve it from the drm_connector created by the bridge. This gets in the way of moving connector creation out of bridge drivers. To make this possible, pass the drm_display_info to drm_bridge_funcs .mode_valid(). Changes to the bridge drivers have been performed with the following coccinelle semantic patch and have been compile-tested. @ rule1 @ identifier funcs; identifier fn; @@ struct drm_bridge_funcs funcs = { ..., .mode_valid = fn }; @ depends on rule1 @ identifier rule1.fn; identifier bridge; identifier mode; @@ enum drm_mode_status fn( struct drm_bridge *bridge, + const struct drm_display_info *info, const struct drm_display_mode *mode ) { ... } Signed-off-by: Laurent Pinchart Reviewed-by: Neil Armstrong Reviewed-by: Boris Brezillon Reviewed-by: Guido Günther # for the nwl-dsi part: Signed-off-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20200526011505.31884-11-laurent.pinchart+renesas@ideasonboard.com

drm: bridge: Return NULL on error from drm_bridge_get_edid()

2020-06-23T17:52:11+00:00

The drm_bridge_get_edid() function is documented to return an error pointer on error. The underlying .get_edid() operation, however, returns NULL on error, and so do the drm_get_edid() and drm_do_get_edid() functions upon which .get_edid() is usually implemented. Make drm_bridge_get_edid() return NULL on error to be consistent. Signed-off-by: Laurent Pinchart Acked-by: Sam Ravnborg Signed-off-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20200526011505.31884-6-laurent.pinchart+renesas@ideasonboard.com

drm: Add helper to create a connector for a chain of bridges

2020-02-26T11:31:41+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 needs to be moved to the display controller driver. To avoid code duplication in display controller drivers, add a new helper to create and manage a DRM connector backed by a chain of bridges. All connector operations are delegating to the appropriate bridge in the chain. Signed-off-by: Laurent Pinchart Reviewed-by: Boris Brezillon Acked-by: Sam Ravnborg Tested-by: Sebastian Reichel Reviewed-by: Sebastian Reichel Signed-off-by: Tomi Valkeinen Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-21-laurent.pinchart@ideasonboard.com