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 <architt@codeaurora.org>
[danvet: Amend kerneldoc as discussed with Archit.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Archit Taneja 2015-05-21 11:03:17 +05:30 committed by Daniel Vetter
parent 862e686ce4
commit 2331b4e476
2 changed files with 107 additions and 0 deletions

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@ -2439,6 +2439,18 @@ void intel_crt_init(struct drm_device *dev)
<title>Tile group</title>
!Pdrivers/gpu/drm/drm_crtc.c Tile group
</sect2>
<sect2>
<title>Bridges</title>
<sect3>
<title>Overview</title>
!Pdrivers/gpu/drm/drm_bridge.c overview
</sect3>
<sect3>
<title>Default bridge callback sequence</title>
!Pdrivers/gpu/drm/drm_bridge.c bridge callbacks
</sect3>
!Edrivers/gpu/drm/drm_bridge.c
</sect2>
</sect1>
<!-- Internals: kms properties -->

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@ -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;