SYNOPSIS

struct drm_crtc_funcs {
void (* reset) (struct drm_crtc *crtc);
int (* cursor_set) (struct drm_crtc *crtc, struct drm_file *file_priv,uint32_t handle, uint32_t width, uint32_t height);
int (* cursor_set2) (struct drm_crtc *crtc, struct drm_file *file_priv,uint32_t handle, uint32_t width, uint32_t height,int32_t hot_x, int32_t hot_y);
int (* cursor_move) (struct drm_crtc *crtc, int x, int y);
void (* gamma_set) (struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,uint32_t start, uint32_t size);
void (* destroy) (struct drm_crtc *crtc);
int (* set_config) (struct drm_mode_set *set);
int (* page_flip) (struct drm_crtc *crtc,struct drm_framebuffer *fb,struct drm_pending_vblank_event *event,uint32_t flags);
int (* set_property) (struct drm_crtc *crtc,struct drm_property *property, uint64_t val);
struct drm_crtc_state *(* atomic_duplicate_state) (struct drm_crtc *crtc);
void (* atomic_destroy_state) (struct drm_crtc *crtc,struct drm_crtc_state *state);
int (* atomic_set_property) (struct drm_crtc *crtc,struct drm_crtc_state *state,struct drm_property *property,uint64_t val);
int (* atomic_get_property) (struct drm_crtc *crtc,const struct drm_crtc_state *state,struct drm_property *property,uint64_t *val);
};

MEMBERS

reset

Reset CRTC hardware and software state to off. This function isn't called by the core directly, only through drm_mode_config_reset. It's not a helper hook only for historical reasons.

Atomic drivers can use drm_atomic_helper_crtc_reset to reset atomic state using this hook.

cursor_set

Update the cursor image. The cursor position is relative to the CRTC and can be partially or fully outside of the visible area.

Note that contrary to all other KMS functions the legacy cursor entry points don't take a framebuffer object, but instead take directly a raw buffer object id from the driver's buffer manager (which is either GEM or TTM for current drivers).

This entry point is deprecated, drivers should instead implement universal plane support and register a proper cursor plane using drm_crtc_init_with_planes.

This callback is optional

RETURNS:

0 on success or a negative error code on failure.

cursor_set2

Update the cursor image, including hotspot information. The hotspot must not affect the cursor position in CRTC coordinates, but is only meant as a hint for virtualized display hardware to coordinate the guests and hosts cursor position. The cursor hotspot is relative to the cursor image. Otherwise this works exactly like cursor_set.

This entry point is deprecated, drivers should instead implement universal plane support and register a proper cursor plane using drm_crtc_init_with_planes.

This callback is optional.

RETURNS:

0 on success or a negative error code on failure.

cursor_move

Update the cursor position. The cursor does not need to be visible when this hook is called.

This entry point is deprecated, drivers should instead implement universal plane support and register a proper cursor plane using drm_crtc_init_with_planes.

This callback is optional.

RETURNS:

0 on success or a negative error code on failure.

gamma_set

Set gamma on the CRTC.

This callback is optional.

NOTE:

Drivers that support gamma tables and also fbdev emulation through the provided helper library need to take care to fill out the gamma hooks for both. Currently there's a bit an unfortunate duplication going on, which should eventually be unified to just one set of hooks.

destroy

Clean up plane resources. This is only called at driver unload time through drm_mode_config_cleanup since a CRTC cannot be hotplugged in DRM.

set_config

This is the main legacy entry point to change the modeset state on a CRTC. All the details of the desired configuration are passed in a struct drm_mode_set - see there for details.

Drivers implementing atomic modeset should use drm_atomic_helper_set_config to implement this hook.

RETURNS:

0 on success or a negative error code on failure.

page_flip

Legacy entry point to schedule a flip to the given framebuffer.

Page flipping is a synchronization mechanism that replaces the frame buffer being scanned out by the CRTC with a new frame buffer during vertical blanking, avoiding tearing (except when requested otherwise through the DRM_MODE_PAGE_FLIP_ASYNC flag). When an application requests a page flip the DRM core verifies that the new frame buffer is large enough to be scanned out by the CRTC in the currently configured mode and then calls the CRTC ->page_flip operation with a pointer to the new frame buffer.

The driver must wait for any pending rendering to the new framebuffer to complete before executing the flip. It should also wait for any pending rendering from other drivers if the underlying buffer is a shared dma-buf.

An application can request to be notified when the page flip has completed. The drm core will supply a struct drm_event in the event parameter in this case. This can be handled by the drm_crtc_send_vblank_event function, which the driver should call on the provided event upon completion of the flip. Note that if the driver supports vblank signalling and timestamping the vblank counters and timestamps must agree with the ones returned from page flip events. With the current vblank helper infrastructure this can be achieved by holding a vblank reference while the page flip is pending, acquired through drm_crtc_vblank_get and released with drm_crtc_vblank_put. Drivers are free to implement their own vblank counter and timestamp tracking though, e.g. if they have accurate timestamp registers in hardware.

FIXME:

Up to that point drivers need to manage events themselves and can use even->base.list freely for that. Specifically they need to ensure that they don't send out page flip (or vblank) events for which the corresponding drm file has been closed already. The drm core unfortunately does not (yet) take care of that. Therefore drivers currently must clean up and release pending events in their ->preclose driver function.

This callback is optional.

NOTE:

Very early versions of the KMS ABI mandated that the driver must block (but not reject) any rendering to the old framebuffer until the flip operation has completed and the old framebuffer is no longer visible. This requirement has been lifted, and userspace is instead expected to request delivery of an event and wait with recycling old buffers until such has been received.

RETURNS:

0 on success or a negative error code on failure. Note that if a ->page_flip operation is already pending the callback should return -EBUSY. Pageflips on a disabled CRTC (either by setting a NULL mode or just runtime disabled through DPMS respectively the new atomic "ACTIVE" state) should result in an -EINVAL error code. Note that drm_atomic_helper_page_flip checks this already for atomic drivers.

set_property

This is the legacy entry point to update a property attached to the CRTC.

Drivers implementing atomic modeset should use drm_atomic_helper_crtc_set_property to implement this hook.

This callback is optional if the driver does not support any legacy driver-private properties.

RETURNS:

0 on success or a negative error code on failure.

atomic_duplicate_state

Duplicate the current atomic state for this CRTC and return it. The core and helpers gurantee that any atomic state duplicated with this hook and still owned by the caller (i.e. not transferred to the driver by calling ->atomic_commit from struct drm_mode_config_funcs) will be cleaned up by calling the atomic_destroy_state hook in this structure.

Atomic drivers which don't subclass struct drm_crtc should use drm_atomic_helper_crtc_duplicate_state. Drivers that subclass the state structure to extend it with driver-private state should use __drm_atomic_helper_crtc_duplicate_state to make sure shared state is duplicated in a consistent fashion across drivers.

It is an error to call this hook before crtc->state has been initialized correctly.

NOTE:

If the duplicate state references refcounted resources this hook must acquire a reference for each of them. The driver must release these references again in atomic_destroy_state.

RETURNS:

Duplicated atomic state or NULL when the allocation failed.

atomic_destroy_state

Destroy a state duplicated with atomic_duplicate_state and release or unreference all resources it references

atomic_set_property

Decode a driver-private property value and store the decoded value into the passed-in state structure. Since the atomic core decodes all standardized properties (even for extensions beyond the core set of properties which might not be implemented by all drivers) this requires drivers to subclass the state structure.

Such driver-private properties should really only be implemented for truly hardware/vendor specific state. Instead it is preferred to standardize atomic extension and decode the properties used to expose such an extension in the core.

Do not call this function directly, use drm_atomic_crtc_set_property instead.

This callback is optional if the driver does not support any driver-private atomic properties.

NOTE:

This function is called in the state assembly 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). Drivers MUST NOT touch any persistent state (hardware or software) or data structures except the passed in state parameter.

Also since userspace controls in which order properties are set this function must not do any input validation (since the state update is incomplete and hence likely inconsistent). Instead any such input validation must be done in the various atomic_check callbacks.

RETURNS:

0 if the property has been found, -EINVAL if the property isn't implemented by the driver (which should never happen, the core only asks for properties attached to this CRTC). No other validation is allowed by the driver. The core already checks that the property value is within the range (integer, valid enum value, ...) the driver set when registering the property.

atomic_get_property

Reads out the decoded driver-private property. This is used to implement the GETCRTC IOCTL.

Do not call this function directly, use drm_atomic_crtc_get_property instead.

This callback is optional if the driver does not support any driver-private atomic properties.

RETURNS:

0 on success, -EINVAL if the property isn't implemented by the driver (which should never happen, the core only asks for properties attached to this CRTC).

DESCRIPTION

The drm_crtc_funcs structure is the central CRTC management structure in the DRM. Each CRTC controls one or more connectors (note that the name CRTC is simply historical, a CRTC may control LVDS, VGA, DVI, TV out, etc. connectors, not just CRTs).

Each driver is responsible for filling out this structure at startup time, in addition to providing other modesetting features, like i2c and DDC bus accessors.

AUTHORS

Jesse Barnes <[email protected]>
Intel Corporation,         
        

Initial version

Laurent Pinchart <[email protected]>
Ideas on board SPRL,         
        

Driver internals

Daniel Vetter <[email protected]>
Intel Corporation,         
        

Contributions all over the place

Lukas Wunner <[email protected]>

vga_switcheroo documentation

COPYRIGHT