From 2331b4e476e0dc705825c8f5462fa1274b6d3b97 Mon Sep 17 00:00:00 2001 From: Archit Taneja Date: Thu, 21 May 2015 11:03:17 +0530 Subject: [PATCH] drm/DocBook: Add more drm_bridge documentation Add DOC sections giving an overview of drm_bridge and how to fill up the drm_bridge_funcs ops. Add these to drm.tpml in DocBook. Add headerdocs for funcs in drm_bridge.c that don't have them yet. Signed-off-by: Archit Taneja [danvet: Amend kerneldoc as discussed with Archit.] Signed-off-by: Daniel Vetter --- Documentation/DocBook/drm.tmpl | 12 +++++ drivers/gpu/drm/drm_bridge.c | 95 ++++++++++++++++++++++++++++++++++ 2 files changed, 107 insertions(+) diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 7c68ecc800a1..5d9d851d8623 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -2439,6 +2439,18 @@ void intel_crt_init(struct drm_device *dev) Tile group !Pdrivers/gpu/drm/drm_crtc.c Tile group + + Bridges + + Overview +!Pdrivers/gpu/drm/drm_bridge.c overview + + + Default bridge callback sequence +!Pdrivers/gpu/drm/drm_bridge.c bridge callbacks + +!Edrivers/gpu/drm/drm_bridge.c + diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index c3a85ce5a7c4..6b8f7211e543 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -28,9 +28,42 @@ #include "drm/drmP.h" +/** + * DOC: overview + * + * drm_bridge represents a device that hangs on to an encoder. These are handy + * when a regular drm_encoder entity isn't enough to represent the entire + * encoder chain. + * + * A bridge is always associated to a single drm_encoder at a time, but can be + * either connected to it directly, or through an intermediate bridge: + * + * encoder ---> bridge B ---> bridge A + * + * Here, the output of the encoder feeds to bridge B, and that furthers feeds to + * bridge A. + * + * The driver using the bridge is responsible to make the associations between + * the encoder and bridges. Once these links are made, the bridges will + * participate along with encoder functions to perform mode_set/enable/disable + * through the ops provided in drm_bridge_funcs. + * + * drm_bridge, like drm_panel, aren't drm_mode_object entities like planes, + * crtcs, encoders or connectors. They just provide additional hooks to get the + * desired output at the end of the encoder chain. + */ + static DEFINE_MUTEX(bridge_lock); static LIST_HEAD(bridge_list); +/** + * drm_bridge_add - add the given bridge to the global bridge list + * + * @bridge: bridge control structure + * + * RETURNS: + * Unconditionally returns Zero. + */ int drm_bridge_add(struct drm_bridge *bridge) { mutex_lock(&bridge_lock); @@ -41,6 +74,11 @@ int drm_bridge_add(struct drm_bridge *bridge) } EXPORT_SYMBOL(drm_bridge_add); +/** + * drm_bridge_remove - remove the given bridge from the global bridge list + * + * @bridge: bridge control structure + */ void drm_bridge_remove(struct drm_bridge *bridge) { mutex_lock(&bridge_lock); @@ -49,6 +87,21 @@ void drm_bridge_remove(struct drm_bridge *bridge) } EXPORT_SYMBOL(drm_bridge_remove); +/** + * drm_bridge_attach - associate given bridge to our DRM device + * + * @dev: DRM device + * @bridge: bridge control structure + * + * called by a kms driver to link one of our encoder/bridge to the given + * bridge. + * + * Note that setting up links between the bridge and our encoder/bridge + * objects needs to be handled by the kms driver itself + * + * RETURNS: + * Zero on success, error code on failure + */ int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge) { if (!dev || !bridge) @@ -66,6 +119,39 @@ int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge) } EXPORT_SYMBOL(drm_bridge_attach); +/** + * DOC: bridge callbacks + * + * The drm_bridge_funcs ops are populated by the bridge driver. The drm + * internals(atomic and crtc helpers) use the helpers defined in drm_bridge.c + * These helpers call a specific drm_bridge_funcs op for all the bridges + * during encoder configuration. + * + * When creating a bridge driver, one can implement drm_bridge_funcs op with + * the help of these rough rules: + * + * pre_enable: this contains things needed to be done for the bridge before + * its clock and timings are enabled by its source. For a bridge, its source + * is generally the encoder or bridge just before it in the encoder chain. + * + * enable: this contains things needed to be done for the bridge once its + * source is enabled. In other words, enable is called once the source is + * ready with clock and timing needed by the bridge. + * + * disable: this contains things needed to be done for the bridge assuming + * that its source is still enabled, i.e. clock and timings are still on. + * + * post_disable: this contains things needed to be done for the bridge once + * its source is disabled, i.e. once clocks and timings are off. + * + * mode_fixup: this should fixup the given mode for the bridge. It is called + * after the encoder's mode fixup. mode_fixup can also reject a mode completely + * if it's unsuitable for the hardware. + * + * mode_set: this sets up the mode for the bridge. It assumes that its source + * (an encoder or a bridge) has set the mode too. + */ + /** * drm_bridge_mode_fixup - fixup proposed mode for all bridges in the * encoder chain @@ -214,6 +300,15 @@ void drm_bridge_enable(struct drm_bridge *bridge) EXPORT_SYMBOL(drm_bridge_enable); #ifdef CONFIG_OF +/** + * of_drm_find_bridge - find the bridge corresponding to the device node in + * the global bridge list + * + * @np: device node + * + * RETURNS: + * drm_bridge control struct on success, NULL on failure + */ struct drm_bridge *of_drm_find_bridge(struct device_node *np) { struct drm_bridge *bridge; -- 2.20.1