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drm: Document drm_connector_helper_funcs

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Nothing special, except the somewhat awkward split in probe helper
callbacks between here and drm_crtc_funcs.

v2: Suggestions from Thierry.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449218769-16577-25-git-send-email-daniel.vetter@ffwll.ch
Reviewed-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Daniel Vetter 2015-12-04 09:46:05 +01:00
parent 11a0ba972d
commit 4ee6034c80
1 changed files with 101 additions and 5 deletions
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106
include/drm/drm_modeset_helper_vtables.h
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@ -270,18 +270,114 @@ static inline void drm_encoder_helper_add(struct drm_encoder *encoder,
/**
* struct drm_connector_helper_funcs - helper operations for connectors
* @get_modes: get mode list for this connector
* @mode_valid: is this mode valid on the given connector? (optional)
* @best_encoder: return the preferred encoder for this connector
* @atomic_best_encoder: atomic version of @best_encoder
*
* The helper operations are called by the mid-layer CRTC helper.
* These functions are used by the atomic and legacy modeset helpers and by the
* probe helpers.
*/
struct drm_connector_helper_funcs {
/**
* @get_modes:
*
* This function should fill in all modes currently valid for the sink
* into the connector->probed_modes list. It should also update the
* EDID property by calling drm_mode_connector_update_edid_property().
*
* The usual way to implement this is to cache the EDID retrieved in the
* probe callback somewhere in the driver-private connector structure.
* In this function drivers then parse the modes in the EDID and add
* them by calling drm_add_edid_modes(). But connectors that driver a
* fixed panel can also manually add specific modes using
* drm_mode_probed_add(). Finally drivers that support audio probably
* want to update the ELD data, too, using drm_edid_to_eld().
*
* This function is only called after the ->detect() hook has indicated
* that a sink is connected and when the EDID isn't overridden through
* sysfs or the kernel commandline.
*
* This callback is used by the probe helpers in e.g.
* drm_helper_probe_single_connector_modes().
*
* RETURNS:
*
* The number of modes added by calling drm_mode_probed_add().
*/
int (*get_modes)(struct drm_connector *connector);
/**
* @mode_valid:
*
* Callback to validate a mode for a connector, irrespective of the
* specific display configuration.
*
* This callback is used by the probe helpers to filter the mode list
* (which is usually derived from the EDID data block from the sink).
* See e.g. drm_helper_probe_single_connector_modes().
*
* NOTE:
*
* This only filters the mode list supplied to userspace in the
* GETCONNECOTR IOCTL. Userspace is free to create modes of its own and
* ask the kernel to use them. It this case the atomic helpers or legacy
* CRTC helpers will not call this function. Drivers therefore must
* still fully validate any mode passed in in a modeset request.
*
* RETURNS:
*
* Either MODE_OK or one of the failure reasons in enum
* &drm_mode_status.
*/
enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
struct drm_display_mode *mode);
/**
* @best_encoder:
*
* This function should select the best encoder for the given connector.
*
* This function is used by both the atomic helpers (in the
* drm_atomic_helper_check_modeset() function) and in the legacy CRTC
* helpers.
*
* NOTE:
*
* In atomic drivers this function is called in the check phase of an
* atomic update. The driver is not allowed to change or inspect
* anything outside of arguments passed-in. Atomic drivers which need to
* inspect dynamic configuration state should instead use
* @atomic_best_encoder.
*
* RETURNS:
*
* Encoder that should be used for the given connector and connector
* state, or NULL if no suitable encoder exists. Note that the helpers
* will ensure that encoders aren't used twice, drivers should not check
* for this.
*/
struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
/**
* @atomic_best_encoder:
*
* This is the atomic version of @best_encoder for atomic drivers which
* need to select the best encoder depending upon the desired
* configuration and can't select it statically.
*
* This function is used by drm_atomic_helper_check_modeset() and either
* this or @best_encoder is required.
*
* 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:
*
* Encoder that should be used for the given connector and connector
* state, or NULL if no suitable encoder exists. Note that the helpers
* will ensure that encoders aren't used twice, drivers should not check
* for this.
*/
struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
struct drm_connector_state *connector_state);
};