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drm: Document drm_encoder/crtc_helper_funcs 

Mostly this is about all the callbacks used for modesets by both legacy
CRTC helpers and atomic helpers and I figured it doesn't make all that
much sense to split this up.

v2: Suggestions from Thierry.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449218769-16577-28-git-send-email-daniel.vetter@ffwll.ch
Reviewed-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Daniel Vetter 2015-12-04 09:46:08 +01:00
parent 30ecad77fe
commit 36b66080dc
1 changed files with 401 additions and 48 deletions
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449
include/drm/drm_modeset_helper_vtables.h
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@ -51,58 +51,236 @@ enum mode_set_atomic;
/**
* struct drm_crtc_helper_funcs - helper operations for CRTCs
* @dpms: set power state
* @prepare: prepare the CRTC, called before @mode_set
* @commit: commit changes to CRTC, called after @mode_set
* @mode_fixup: try to fixup proposed mode for this CRTC
* @mode_set: set this mode
* @mode_set_nofb: set mode only (no scanout buffer attached)
* @mode_set_base: update the scanout buffer
* @mode_set_base_atomic: non-blocking mode set (used for kgdb support)
* @load_lut: load color palette
* @disable: disable CRTC when no longer in use
* @enable: enable CRTC
*
* The helper operations are called by the mid-layer CRTC helper.
*
* Note that with atomic helpers @dpms, @prepare and @commit hooks are
* deprecated. Used @enable and @disable instead exclusively.
*
* With legacy crtc helpers there's a big semantic difference between @disable
* and the other hooks: @disable also needs to release any resources acquired in
* @mode_set (like shared PLLs).
* These hooks are used by the legacy CRTC helpers, the transitional plane
* helpers and the new atomic modesetting helpers.
*/
struct drm_crtc_helper_funcs {
/*
* Control power levels on the CRTC. If the mode passed in is
* unsupported, the provider must use the next lowest power level.
/**
* @dpms:
*
* Callback to control power levels on the CRTC. If the mode passed in
* is unsupported, the provider must use the next lowest power level.
* This is used by the legacy CRTC helpers to implement DPMS
* functionality in drm_helper_connector_dpms().
*
* This callback is also used to disable a CRTC by calling it with
* DRM_MODE_DPMS_OFF if the @disable hook isn't used.
*
* This callback is used by the legacy CRTC helpers. Atomic helpers
* also support using this hook for enabling and disabling a CRTC to
* facilitate transitions to atomic, but it is deprecated. Instead
* @enable and @disable should be used.
*/
void (*dpms)(struct drm_crtc *crtc, int mode);
/**
* @prepare:
*
* This callback should prepare the CRTC for a subsequent modeset, which
* in practice means the driver should disable the CRTC if it is
* running. Most drivers ended up implementing this by calling their
* @dpms hook with DRM_MODE_DPMS_OFF.
*
* This callback is used by the legacy CRTC helpers. Atomic helpers
* also support using this hook for disabling a CRTC to facilitate
* transitions to atomic, but it is deprecated. Instead @disable should
* be used.
*/
void (*prepare)(struct drm_crtc *crtc);
/**
* @commit:
*
* This callback should commit the new mode on the CRTC after a modeset,
* which in practice means the driver should enable the CRTC. Most
* drivers ended up implementing this by calling their @dpms hook with
* DRM_MODE_DPMS_ON.
*
* This callback is used by the legacy CRTC helpers. Atomic helpers
* also support using this hook for enabling a CRTC to facilitate
* transitions to atomic, but it is deprecated. Instead @enable should
* be used.
*/
void (*commit)(struct drm_crtc *crtc);
/* Provider can fixup or change mode timings before modeset occurs */
/**
* @mode_fixup:
*
* This callback is used to validate a mode. The parameter mode is the
* display mode that userspace requested, adjusted_mode is the mode the
* encoders need to be fed with. Note that this is the inverse semantics
* of the meaning for the &drm_encoder and &drm_bridge
* ->mode_fixup() functions. If the CRTC cannot support the requested
* conversion from mode to adjusted_mode it should reject the modeset.
*
* This function is used by both legacy CRTC helpers and atomic helpers.
* With atomic helpers it is optional.
*
* NOTE:
*
* This function is called in the check phase of atomic modesets, which
* can be aborted for any reason (including on userspace's request to
* just check whether a configuration would be possible). Atomic drivers
* MUST NOT touch any persistent state (hardware or software) or data
* structures except the passed in adjusted_mode parameter.
*
* This is in contrast to the legacy CRTC helpers where this was
* allowed.
*
* Atomic drivers which need to inspect and adjust more state should
* instead use the @atomic_check callback.
*
* RETURNS:
*
* True if an acceptable configuration is possible, false if the modeset
* operation should be rejected.
*/
bool (*mode_fixup)(struct drm_crtc *crtc,
const struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode);
/* Actually set the mode */
/**
* @mode_set:
*
* This callback is used by the legacy CRTC helpers to set a new mode,
* position and framebuffer. Since it ties the primary plane to every
* mode change it is incompatible with universal plane support. And
* since it can't update other planes it's incompatible with atomic
* modeset support.
*
* This callback is only used by CRTC helpers and deprecated.
*
* RETURNS:
*
* 0 on success or a negative error code on failure.
*/
int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode, int x, int y,
struct drm_framebuffer *old_fb);
/* Actually set the mode for atomic helpers, optional */
/**
* @mode_set_nofb:
*
* This callback is used to update the display mode of a CRTC without
* changing anything of the primary plane configuration. This fits the
* requirement of atomic and hence is used by the atomic helpers. It is
* also used by the transitional plane helpers to implement a
* @mode_set hook in drm_helper_crtc_mode_set().
*
* Note that the display pipe is completely off when this function is
* called. Atomic drivers which need hardware to be running before they
* program the new display mode (e.g. because they implement runtime PM)
* should not use this hook. This is because the helper library calls
* this hook only once per mode change and not every time the display
* pipeline is suspended using either DPMS or the new "ACTIVE" property.
* Which means register values set in this callback might get reset when
* the CRTC is suspended, but not restored. Such drivers should instead
* move all their CRTC setup into the @enable callback.
*
* This callback is optional.
*/
void (*mode_set_nofb)(struct drm_crtc *crtc);
/* Move the crtc on the current fb to the given position *optional* */
/**
* @mode_set_base:
*
* This callback is used by the legacy CRTC helpers to set a new
* framebuffer and scanout position. It is optional and used as an
* optimized fast-path instead of a full mode set operation with all the
* resulting flickering. Since it can't update other planes it's
* incompatible with atomic modeset support.
*
* This callback is only used by the CRTC helpers and deprecated.
*
* RETURNS:
*
* 0 on success or a negative error code on failure.
*/
int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
struct drm_framebuffer *old_fb);
/**
* @mode_set_base_atomic:
*
* This callback is used by the fbdev helpers to set a new framebuffer
* and scanout without sleeping, i.e. from an atomic calling context. It
* is only used to implement kgdb support.
*
* This callback is optional and only needed for kgdb support in the fbdev
* helpers.
*
* RETURNS:
*
* 0 on success or a negative error code on failure.
*/
int (*mode_set_base_atomic)(struct drm_crtc *crtc,
struct drm_framebuffer *fb, int x, int y,
enum mode_set_atomic);
/* reload the current crtc LUT */
/**
* @load_lut:
*
* Load a LUT prepared with the @gamma_set functions from
* &drm_fb_helper_funcs.
*
* This callback is optional and is only used by the fbdev emulation
* helpers.
*
* FIXME:
*
* This callback is functionally redundant with the core gamma table
* support and simply exists because the fbdev hasn't yet been
* refactored to use the core gamma table interfaces.
*/
void (*load_lut)(struct drm_crtc *crtc);
/**
* @disable:
*
* This callback should be used to disable the CRTC. With the atomic
* drivers it is called after all encoders connected to this CRTC have
* been shut off already using their own ->disable hook. If that
* sequence is too simple drivers can just add their own hooks and call
* it from this CRTC callback here by looping over all encoders
* connected to it using for_each_encoder_on_crtc().
*
* This hook is used both by legacy CRTC helpers and atomic helpers.
* Atomic drivers don't need to implement it if there's no need to
* disable anything at the CRTC level. To ensure that runtime PM
* handling (using either DPMS or the new "ACTIVE" property) works
* @disable must be the inverse of @enable for atomic drivers.
*
* NOTE:
*
* With legacy CRTC helpers there's a big semantic difference between
* @disable and other hooks (like @prepare or @dpms) used to shut down a
* CRTC: @disable is only called when also logically disabling the
* display pipeline and needs to release any resources acquired in
* @mode_set (like shared PLLs, or again release pinned framebuffers).
*
* Therefore @disable must be the inverse of @mode_set plus @commit for
* drivers still using legacy CRTC helpers, which is different from the
* rules under atomic.
*/
void (*disable)(struct drm_crtc *crtc);
/**
* @enable:
*
* This callback should be used to enable the CRTC. With the atomic
* drivers it is called before all encoders connected to this CRTC are
* enabled through the encoder's own ->enable hook. If that sequence is
* too simple drivers can just add their own hooks and call it from this
* CRTC callback here by looping over all encoders connected to it using
* for_each_encoder_on_crtc().
*
* This hook is used only by atomic helpers, for symmetry with @disable.
* Atomic drivers don't need to implement it if there's no need to
* enable anything at the CRTC level. To ensure that runtime PM handling
* (using either DPMS or the new "ACTIVE" property) works
* @enable must be the inverse of @disable for atomic drivers.
*/
void (*enable)(struct drm_crtc *crtc);
/**
@ -212,53 +390,228 @@ static inline void drm_crtc_helper_add(struct drm_crtc *crtc,
/**
* struct drm_encoder_helper_funcs - helper operations for encoders
* @dpms: set power state
* @mode_fixup: try to fixup proposed mode for this connector
* @prepare: part of the disable sequence, called before the CRTC modeset
* @commit: called after the CRTC modeset
* @mode_set: set this mode, optional for atomic helpers
* @get_crtc: return CRTC that the encoder is currently attached to
* @detect: connection status detection
* @disable: disable encoder when not in use (overrides DPMS off)
* @enable: enable encoder
* @atomic_check: check for validity of an atomic update
*
* The helper operations are called by the mid-layer CRTC helper.
*
* Note that with atomic helpers @dpms, @prepare and @commit hooks are
* deprecated. Used @enable and @disable instead exclusively.
*
* With legacy crtc helpers there's a big semantic difference between @disable
* and the other hooks: @disable also needs to release any resources acquired in
* @mode_set (like shared PLLs).
* These hooks are used by the legacy CRTC helpers, the transitional plane
* helpers and the new atomic modesetting helpers.
*/
struct drm_encoder_helper_funcs {
/**
* @dpms:
*
* Callback to control power levels on the encoder. If the mode passed in
* is unsupported, the provider must use the next lowest power level.
* This is used by the legacy encoder helpers to implement DPMS
* functionality in drm_helper_connector_dpms().
*
* This callback is also used to disable an encoder by calling it with
* DRM_MODE_DPMS_OFF if the @disable hook isn't used.
*
* This callback is used by the legacy CRTC helpers. Atomic helpers
* also support using this hook for enabling and disabling an encoder to
* facilitate transitions to atomic, but it is deprecated. Instead
* @enable and @disable should be used.
*/
void (*dpms)(struct drm_encoder *encoder, int mode);
/**
* @mode_fixup:
*
* This callback is used to validate and adjust a mode. The parameter
* mode is the display mode that should be fed to the next element in
* the display chain, either the final &drm_connector or a &drm_bridge.
* The parameter adjusted_mode is the input mode the encoder requires. It
* can be modified by this callback and does not need to match mode.
*
* This function is used by both legacy CRTC helpers and atomic helpers.
* With atomic helpers it is optional.
*
* NOTE:
*
* This function is called in the check phase of atomic modesets, which
* can be aborted for any reason (including on userspace's request to
* just check whether a configuration would be possible). Atomic drivers
* MUST NOT touch any persistent state (hardware or software) or data
* structures except the passed in adjusted_mode parameter.
*
* This is in contrast to the legacy CRTC helpers where this was
* allowed.
*
* Atomic drivers which need to inspect and adjust more state should
* instead use the @atomic_check callback.
*
* RETURNS:
*
* True if an acceptable configuration is possible, false if the modeset
* operation should be rejected.
*/
bool (*mode_fixup)(struct drm_encoder *encoder,
const struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode);
/**
* @prepare:
*
* This callback should prepare the encoder for a subsequent modeset,
* which in practice means the driver should disable the encoder if it
* is running. Most drivers ended up implementing this by calling their
* @dpms hook with DRM_MODE_DPMS_OFF.
*
* This callback is used by the legacy CRTC helpers. Atomic helpers
* also support using this hook for disabling an encoder to facilitate
* transitions to atomic, but it is deprecated. Instead @disable should
* be used.
*/
void (*prepare)(struct drm_encoder *encoder);
/**
* @commit:
*
* This callback should commit the new mode on the encoder after a modeset,
* which in practice means the driver should enable the encoder. Most
* drivers ended up implementing this by calling their @dpms hook with
* DRM_MODE_DPMS_ON.
*
* This callback is used by the legacy CRTC helpers. Atomic helpers
* also support using this hook for enabling an encoder to facilitate
* transitions to atomic, but it is deprecated. Instead @enable should
* be used.
*/
void (*commit)(struct drm_encoder *encoder);
/**
* @mode_set:
*
* This callback is used to update the display mode of an encoder.
*
* Note that the display pipe is completely off when this function is
* called. Drivers which need hardware to be running before they program
* the new display mode (because they implement runtime PM) should not
* use this hook, because the helper library calls it only once and not
* every time the display pipeline is suspend using either DPMS or the
* new "ACTIVE" property. Such drivers should instead move all their
* encoder setup into the ->enable() callback.
*
* This callback is used both by the legacy CRTC helpers and the atomic
* modeset helpers. It is optional in the atomic helpers.
*/
void (*mode_set)(struct drm_encoder *encoder,
struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode);
/**
* @get_crtc:
*
* This callback is used by the legacy CRTC helpers to work around
* deficiencies in its own book-keeping.
*
* Do not use, use atomic helpers instead, which get the book keeping
* right.
*
* FIXME:
*
* Currently only nouveau is using this, and as soon as nouveau is
* atomic we can ditch this hook.
*/
struct drm_crtc *(*get_crtc)(struct drm_encoder *encoder);
/* detect for DAC style encoders */
/**
* @detect:
*
* This callback can be used by drivers who want to do detection on the
* encoder object instead of in connector functions.
*
* It is not used by any helper and therefore has purely driver-specific
* semantics. New drivers shouldn't use this and instead just implement
* their own private callbacks.
*
* FIXME:
*
* This should just be converted into a pile of driver vfuncs.
* Currently radeon, amdgpu and nouveau are using it.
*/
enum drm_connector_status (*detect)(struct drm_encoder *encoder,
struct drm_connector *connector);
/**
* @disable:
*
* This callback should be used to disable the encoder. With the atomic
* drivers it is called before this encoder's CRTC has been shut off
* using the CRTC's own ->disable hook. If that sequence is too simple
* drivers can just add their own driver private encoder hooks and call
* them from CRTC's callback by looping over all encoders connected to
* it using for_each_encoder_on_crtc().
*
* This hook is used both by legacy CRTC helpers and atomic helpers.
* Atomic drivers don't need to implement it if there's no need to
* disable anything at the encoder level. To ensure that runtime PM
* handling (using either DPMS or the new "ACTIVE" property) works
* @disable must be the inverse of @enable for atomic drivers.
*
* NOTE:
*
* With legacy CRTC helpers there's a big semantic difference between
* @disable and other hooks (like @prepare or @dpms) used to shut down a
* encoder: @disable is only called when also logically disabling the
* display pipeline and needs to release any resources acquired in
* @mode_set (like shared PLLs, or again release pinned framebuffers).
*
* Therefore @disable must be the inverse of @mode_set plus @commit for
* drivers still using legacy CRTC helpers, which is different from the
* rules under atomic.
*/
void (*disable)(struct drm_encoder *encoder);
/**
* @enable:
*
* This callback should be used to enable the encoder. With the atomic
* drivers it is called after this encoder's CRTC has been enabled using
* the CRTC's own ->enable hook. If that sequence is too simple drivers
* can just add their own driver private encoder hooks and call them
* from CRTC's callback by looping over all encoders connected to it
* using for_each_encoder_on_crtc().
*
* This hook is used only by atomic helpers, for symmetry with @disable.
* Atomic drivers don't need to implement it if there's no need to
* enable anything at the encoder level. To ensure that runtime PM handling
* (using either DPMS or the new "ACTIVE" property) works
* @enable must be the inverse of @disable for atomic drivers.
*/
void (*enable)(struct drm_encoder *encoder);
/* atomic helpers */
/**
* @atomic_check:
*
* This callback is used to validate encoder state for atomic drivers.
* Since the encoder is the object connecting the CRTC and connector it
* gets passed both states, to be able to validate interactions and
* update the CRTC to match what the encoder needs for the requested
* connector.
*
* This function is used by the atomic helpers, but it is optional.
*
* NOTE:
*
* This function is called in the check phase of an atomic update. The
* driver is not allowed to change anything outside of the free-standing
* state objects passed-in or assembled in the overall &drm_atomic_state
* update tracking structure.
*
* RETURNS:
*
* 0 on success, -EINVAL if the state or the transition can't be
* supported, -ENOMEM on memory allocation failure and -EDEADLK if an
* attempt to obtain another state object ran into a &drm_modeset_lock
* deadlock.
*/
int (*atomic_check)(struct drm_encoder *encoder,
struct drm_crtc_state *crtc_state,
struct drm_connector_state *conn_state);
};
/**
* drm_encoder_helper_add - sets the helper vtable for a encoder
* drm_encoder_helper_add - sets the helper vtable for an encoder
* @encoder: DRM encoder
* @funcs: helper vtable to set for @encoder
*/