Commit c9e42b72 authored by Daniel Vetter's avatar Daniel Vetter

drm: Document kms locking a bit better

The rules are getting real hard, better to dump my brain into text a
bit. This is by far not complete, but I think I reasonable start at
least.

Some of the older kms structures would need a full doc review anyway
...

Cc: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: default avatarHarry Wentland <harry.wentland@amd.com>
Reviewed-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170328155349.5972-2-daniel.vetter@ffwll.ch
parent 75b94cd9
......@@ -656,7 +656,6 @@ struct drm_cmdline_mode {
* @bad_edid_counter: track sinks that give us an EDID with invalid checksum
* @edid_corrupt: indicates whether the last read EDID was corrupt
* @debugfs_entry: debugfs directory for this connector
* @state: current atomic state for this connector
* @has_tile: is this connector connected to a tiled monitor
* @tile_group: tile group for the connected monitor
* @tile_is_single_monitor: whether the tile is one monitor housing
......@@ -824,6 +823,21 @@ struct drm_connector {
struct dentry *debugfs_entry;
/**
* @state:
*
* Current atomic state for this connector.
*
* This is protected by @drm_mode_config.connection_mutex. Note that
* nonblocking atomic commits access the current connector state without
* taking locks. Either by going through the &struct drm_atomic_state
* pointers, see for_each_connector_in_state(),
* for_each_oldnew_connector_in_state(),
* for_each_old_connector_in_state() and
* for_each_new_connector_in_state(). Or through careful ordering of
* atomic commit operations as implemented in the atomic helpers, see
* &struct drm_crtc_commit.
*/
struct drm_connector_state *state;
/* DisplayID bits */
......
......@@ -699,10 +699,12 @@ struct drm_crtc {
/**
* @mutex:
*
* This provides a read lock for the overall crtc state (mode, dpms
* This provides a read lock for the overall CRTC state (mode, dpms
* state, ...) and a write lock for everything which can be update
* without a full modeset (fb, cursor data, crtc properties ...). A full
* without a full modeset (fb, cursor data, CRTC properties ...). A full
* modeset also need to grab &drm_mode_config.connection_mutex.
*
* For atomic drivers specifically this protects @state.
*/
struct drm_modeset_lock mutex;
......@@ -748,6 +750,14 @@ struct drm_crtc {
* @state:
*
* Current atomic state for this CRTC.
*
* This is protected by @mutex. Note that nonblocking atomic commits
* access the current CRTC state without taking locks. Either by going
* through the &struct drm_atomic_state pointers, see
* for_each_crtc_in_state(), for_each_oldnew_crtc_in_state(),
* for_each_old_crtc_in_state() and for_each_new_crtc_in_state(). Or
* through careful ordering of atomic commit operations as implemented
* in the atomic helpers, see &struct drm_crtc_commit.
*/
struct drm_crtc_state *state;
......
......@@ -307,21 +307,6 @@ struct drm_mode_config_funcs {
/**
* struct drm_mode_config - Mode configuration control structure
* @mutex: mutex protecting KMS related lists and structures
* @connection_mutex: ww mutex protecting connector state and routing
* @acquire_ctx: global implicit acquire context used by atomic drivers for
* legacy IOCTLs
* @fb_lock: mutex to protect fb state and lists
* @num_fb: number of fbs available
* @fb_list: list of framebuffers available
* @num_encoder: number of encoders on this device
* @encoder_list: list of encoder objects
* @num_overlay_plane: number of overlay planes on this device
* @num_total_plane: number of universal (i.e. with primary/curso) planes on this device
* @plane_list: list of plane objects
* @num_crtc: number of CRTCs on this device
* @crtc_list: list of CRTC objects
* @property_list: list of property objects
* @min_width: minimum pixel width on this device
* @min_height: minimum pixel height on this device
* @max_width: maximum pixel width on this device
......@@ -332,9 +317,6 @@ struct drm_mode_config_funcs {
* @poll_running: track polling status for this device
* @delayed_event: track delayed poll uevent deliver for this device
* @output_poll_work: delayed work for polling in process context
* @property_blob_list: list of all the blob property objects
* @blob_lock: mutex for blob property allocation and management
* @*_property: core property tracking
* @preferred_depth: preferred RBG pixel depth, used by fb helpers
* @prefer_shadow: hint to userspace to prefer shadow-fb rendering
* @cursor_width: hint to userspace for max cursor width
......@@ -346,9 +328,37 @@ struct drm_mode_config_funcs {
* global restrictions are also here, e.g. dimension restrictions.
*/
struct drm_mode_config {
struct mutex mutex; /* protects configuration (mode lists etc.) */
struct drm_modeset_lock connection_mutex; /* protects connector->encoder and encoder->crtc links */
struct drm_modeset_acquire_ctx *acquire_ctx; /* for legacy _lock_all() / _unlock_all() */
/**
* @mutex:
*
* This is the big scary modeset BKL which protects everything that
* isn't protect otherwise. Scope is unclear and fuzzy, try to remove
* anything from under it's protection and move it into more well-scoped
* locks.
*
* The one important thing this protects is the use of @acquire_ctx.
*/
struct mutex mutex;
/**
* @connection_mutex:
*
* This protects connector state and the connector to encoder to CRTC
* routing chain.
*
* For atomic drivers specifically this protects &drm_connector.state.
*/
struct drm_modeset_lock connection_mutex;
/**
* @acquire_ctx:
*
* Global implicit acquire context used by atomic drivers for legacy
* IOCTLs. Deprecated, since implicit locking contexts make it
* impossible to use driver-private &struct drm_modeset_lock. Users of
* this must hold @mutex.
*/
struct drm_modeset_acquire_ctx *acquire_ctx;
/**
* @idr_mutex:
......@@ -374,8 +384,11 @@ struct drm_mode_config {
*/
struct idr tile_idr;
struct mutex fb_lock; /* proctects global and per-file fb lists */
/** @fb_lock: Mutex to protect fb the global @fb_list and @num_fb. */
struct mutex fb_lock;
/** @num_fb: Number of entries on @fb_list. */
int num_fb;
/** @fb_list: List of all &struct drm_framebuffer. */
struct list_head fb_list;
/**
......@@ -393,27 +406,80 @@ struct drm_mode_config {
*/
struct ida connector_ida;
/**
* @connector_list: List of connector objects. Protected by
* @connector_list_lock. Only use drm_for_each_connector_iter() and
* @connector_list:
*
* List of connector objects linked with &drm_connector.head. Protected
* by @connector_list_lock. Only use drm_for_each_connector_iter() and
* &struct drm_connector_list_iter to walk this list.
*/
struct list_head connector_list;
/**
* @num_encoder:
*
* Number of encoders on this device. This is invariant over the
* lifetime of a device and hence doesn't need any locks.
*/
int num_encoder;
/**
* @encoder_list:
*
* List of encoder objects linked with &drm_encoder.head. This is
* invariant over the lifetime of a device and hence doesn't need any
* locks.
*/
struct list_head encoder_list;
/*
* Track # of overlay planes separately from # of total planes. By
* default we only advertise overlay planes to userspace; if userspace
* sets the "universal plane" capability bit, we'll go ahead and
* expose all planes.
/**
* @num_overlay_plane:
*
* Number of overlay planes on this device, excluding primary and cursor
* planes.
*
* Track number of overlay planes separately from number of total
* planes. By default we only advertise overlay planes to userspace; if
* userspace sets the "universal plane" capability bit, we'll go ahead
* and expose all planes. This is invariant over the lifetime of a
* device and hence doesn't need any locks.
*/
int num_overlay_plane;
/**
* @num_total_plane:
*
* Number of universal (i.e. with primary/curso) planes on this device.
* This is invariant over the lifetime of a device and hence doesn't
* need any locks.
*/
int num_total_plane;
/**
* @plane_list:
*
* List of plane objects linked with &drm_plane.head. This is invariant
* over the lifetime of a device and hence doesn't need any locks.
*/
struct list_head plane_list;
/**
* @num_crtc:
*
* Number of CRTCs on this device linked with &drm_crtc.head. This is invariant over the lifetime
* of a device and hence doesn't need any locks.
*/
int num_crtc;
/**
* @crtc_list:
*
* List of CRTC objects linked with &drm_crtc.head. This is invariant
* over the lifetime of a device and hence doesn't need any locks.
*/
struct list_head crtc_list;
/**
* @property_list:
*
* List of property type objects linked with &drm_property.head. This is
* invariant over the lifetime of a device and hence doesn't need any
* locks.
*/
struct list_head property_list;
int min_width, min_height;
......@@ -427,10 +493,24 @@ struct drm_mode_config {
bool delayed_event;
struct delayed_work output_poll_work;
/**
* @blob_lock:
*
* Mutex for blob property allocation and management, protects
* @property_blob_list and &drm_file.blobs.
*/
struct mutex blob_lock;
/* pointers to standard properties */
/**
* @property_blob_list:
*
* List of all the blob property objects linked with
* &drm_property_blob.head. Protected by @blob_lock.
*/
struct list_head property_blob_list;
/* pointers to standard properties */
/**
* @edid_property: Default connector property to hold the EDID of the
* currently connected sink, if any.
......
......@@ -456,7 +456,6 @@ enum drm_plane_type {
* @funcs: helper functions
* @properties: property tracking for this plane
* @type: type of plane (overlay, primary, cursor)
* @state: current atomic state for this plane
* @zpos_property: zpos property for this plane
* @rotation_property: rotation property for this plane
* @helper_private: mid-layer private data
......@@ -473,6 +472,8 @@ struct drm_plane {
* Protects modeset plane state, together with the &drm_crtc.mutex of
* CRTC this plane is linked to (when active, getting activated or
* getting disabled).
*
* For atomic drivers specifically this protects @state.
*/
struct drm_modeset_lock mutex;
......@@ -502,6 +503,19 @@ struct drm_plane {
const struct drm_plane_helper_funcs *helper_private;
/**
* @state:
*
* Current atomic state for this plane.
*
* This is protected by @mutex. Note that nonblocking atomic commits
* access the current plane state without taking locks. Either by going
* through the &struct drm_atomic_state pointers, see
* for_each_plane_in_state(), for_each_oldnew_plane_in_state(),
* for_each_old_plane_in_state() and for_each_new_plane_in_state(). Or
* through careful ordering of atomic commit operations as implemented
* in the atomic helpers, see &struct drm_crtc_commit.
*/
struct drm_plane_state *state;
struct drm_property *zpos_property;
......
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