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>
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Daniel Vetter
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36b66080dc
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@ -51,58 +51,236 @@ enum mode_set_atomic;
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/**
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* struct drm_crtc_helper_funcs - helper operations for CRTCs
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* @dpms: set power state
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* @prepare: prepare the CRTC, called before @mode_set
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* @commit: commit changes to CRTC, called after @mode_set
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* @mode_fixup: try to fixup proposed mode for this CRTC
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* @mode_set: set this mode
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* @mode_set_nofb: set mode only (no scanout buffer attached)
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* @mode_set_base: update the scanout buffer
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* @mode_set_base_atomic: non-blocking mode set (used for kgdb support)
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* @load_lut: load color palette
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* @disable: disable CRTC when no longer in use
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* @enable: enable CRTC
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*
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* The helper operations are called by the mid-layer CRTC helper.
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*
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* Note that with atomic helpers @dpms, @prepare and @commit hooks are
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* deprecated. Used @enable and @disable instead exclusively.
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*
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* With legacy crtc helpers there's a big semantic difference between @disable
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* and the other hooks: @disable also needs to release any resources acquired in
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* @mode_set (like shared PLLs).
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* These hooks are used by the legacy CRTC helpers, the transitional plane
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* helpers and the new atomic modesetting helpers.
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*/
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struct drm_crtc_helper_funcs {
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/*
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* Control power levels on the CRTC. If the mode passed in is
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* unsupported, the provider must use the next lowest power level.
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/**
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* @dpms:
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*
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* Callback to control power levels on the CRTC. If the mode passed in
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* is unsupported, the provider must use the next lowest power level.
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* This is used by the legacy CRTC helpers to implement DPMS
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* functionality in drm_helper_connector_dpms().
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*
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* This callback is also used to disable a CRTC by calling it with
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* DRM_MODE_DPMS_OFF if the @disable hook isn't used.
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*
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* This callback is used by the legacy CRTC helpers. Atomic helpers
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* also support using this hook for enabling and disabling a CRTC to
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* facilitate transitions to atomic, but it is deprecated. Instead
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* @enable and @disable should be used.
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*/
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void (*dpms)(struct drm_crtc *crtc, int mode);
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/**
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* @prepare:
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*
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* This callback should prepare the CRTC for a subsequent modeset, which
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* in practice means the driver should disable the CRTC if it is
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* running. Most drivers ended up implementing this by calling their
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* @dpms hook with DRM_MODE_DPMS_OFF.
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*
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* This callback is used by the legacy CRTC helpers. Atomic helpers
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* also support using this hook for disabling a CRTC to facilitate
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* transitions to atomic, but it is deprecated. Instead @disable should
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* be used.
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*/
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void (*prepare)(struct drm_crtc *crtc);
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/**
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* @commit:
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*
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* This callback should commit the new mode on the CRTC after a modeset,
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* which in practice means the driver should enable the CRTC. Most
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* drivers ended up implementing this by calling their @dpms hook with
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* DRM_MODE_DPMS_ON.
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*
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* This callback is used by the legacy CRTC helpers. Atomic helpers
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* also support using this hook for enabling a CRTC to facilitate
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* transitions to atomic, but it is deprecated. Instead @enable should
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* be used.
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*/
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void (*commit)(struct drm_crtc *crtc);
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/* Provider can fixup or change mode timings before modeset occurs */
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/**
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* @mode_fixup:
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*
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* This callback is used to validate a mode. The parameter mode is the
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* display mode that userspace requested, adjusted_mode is the mode the
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* encoders need to be fed with. Note that this is the inverse semantics
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* of the meaning for the &drm_encoder and &drm_bridge
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* ->mode_fixup() functions. If the CRTC cannot support the requested
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* conversion from mode to adjusted_mode it should reject the modeset.
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*
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* This function is used by both legacy CRTC helpers and atomic helpers.
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* With atomic helpers it is optional.
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*
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* NOTE:
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*
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* This function is called in the check phase of atomic modesets, which
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* can be aborted for any reason (including on userspace's request to
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* just check whether a configuration would be possible). Atomic drivers
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* MUST NOT touch any persistent state (hardware or software) or data
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* structures except the passed in adjusted_mode parameter.
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*
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* This is in contrast to the legacy CRTC helpers where this was
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* allowed.
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*
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* Atomic drivers which need to inspect and adjust more state should
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* instead use the @atomic_check callback.
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*
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* RETURNS:
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*
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* True if an acceptable configuration is possible, false if the modeset
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* operation should be rejected.
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*/
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bool (*mode_fixup)(struct drm_crtc *crtc,
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const struct drm_display_mode *mode,
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struct drm_display_mode *adjusted_mode);
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/* Actually set the mode */
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/**
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* @mode_set:
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*
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* This callback is used by the legacy CRTC helpers to set a new mode,
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* position and framebuffer. Since it ties the primary plane to every
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* mode change it is incompatible with universal plane support. And
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* since it can't update other planes it's incompatible with atomic
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* modeset support.
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*
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* This callback is only used by CRTC helpers and deprecated.
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*
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* RETURNS:
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*
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* 0 on success or a negative error code on failure.
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*/
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int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
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struct drm_display_mode *adjusted_mode, int x, int y,
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struct drm_framebuffer *old_fb);
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/* Actually set the mode for atomic helpers, optional */
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/**
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* @mode_set_nofb:
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*
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* This callback is used to update the display mode of a CRTC without
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* changing anything of the primary plane configuration. This fits the
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* requirement of atomic and hence is used by the atomic helpers. It is
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* also used by the transitional plane helpers to implement a
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* @mode_set hook in drm_helper_crtc_mode_set().
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*
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* Note that the display pipe is completely off when this function is
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* called. Atomic drivers which need hardware to be running before they
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* program the new display mode (e.g. because they implement runtime PM)
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* should not use this hook. This is because the helper library calls
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* this hook only once per mode change and not every time the display
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* pipeline is suspended using either DPMS or the new "ACTIVE" property.
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* Which means register values set in this callback might get reset when
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* the CRTC is suspended, but not restored. Such drivers should instead
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* move all their CRTC setup into the @enable callback.
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*
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* This callback is optional.
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*/
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void (*mode_set_nofb)(struct drm_crtc *crtc);
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/* Move the crtc on the current fb to the given position *optional* */
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/**
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* @mode_set_base:
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*
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* This callback is used by the legacy CRTC helpers to set a new
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* framebuffer and scanout position. It is optional and used as an
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* optimized fast-path instead of a full mode set operation with all the
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* resulting flickering. Since it can't update other planes it's
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* incompatible with atomic modeset support.
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*
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* This callback is only used by the CRTC helpers and deprecated.
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*
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* RETURNS:
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*
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* 0 on success or a negative error code on failure.
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*/
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int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
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struct drm_framebuffer *old_fb);
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/**
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* @mode_set_base_atomic:
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*
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* This callback is used by the fbdev helpers to set a new framebuffer
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* and scanout without sleeping, i.e. from an atomic calling context. It
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* is only used to implement kgdb support.
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*
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* This callback is optional and only needed for kgdb support in the fbdev
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* helpers.
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*
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* RETURNS:
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*
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* 0 on success or a negative error code on failure.
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*/
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int (*mode_set_base_atomic)(struct drm_crtc *crtc,
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struct drm_framebuffer *fb, int x, int y,
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enum mode_set_atomic);
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/* reload the current crtc LUT */
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/**
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* @load_lut:
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*
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* Load a LUT prepared with the @gamma_set functions from
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* &drm_fb_helper_funcs.
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*
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* This callback is optional and is only used by the fbdev emulation
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* helpers.
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*
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* FIXME:
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*
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* This callback is functionally redundant with the core gamma table
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* support and simply exists because the fbdev hasn't yet been
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* refactored to use the core gamma table interfaces.
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*/
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void (*load_lut)(struct drm_crtc *crtc);
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/**
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* @disable:
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*
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* This callback should be used to disable the CRTC. With the atomic
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* drivers it is called after all encoders connected to this CRTC have
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* been shut off already using their own ->disable hook. If that
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* sequence is too simple drivers can just add their own hooks and call
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* it from this CRTC callback here by looping over all encoders
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* connected to it using for_each_encoder_on_crtc().
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*
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* This hook is used both by legacy CRTC helpers and atomic helpers.
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* Atomic drivers don't need to implement it if there's no need to
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* disable anything at the CRTC level. To ensure that runtime PM
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* handling (using either DPMS or the new "ACTIVE" property) works
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* @disable must be the inverse of @enable for atomic drivers.
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*
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* NOTE:
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*
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* With legacy CRTC helpers there's a big semantic difference between
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* @disable and other hooks (like @prepare or @dpms) used to shut down a
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* CRTC: @disable is only called when also logically disabling the
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* display pipeline and needs to release any resources acquired in
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* @mode_set (like shared PLLs, or again release pinned framebuffers).
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*
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* Therefore @disable must be the inverse of @mode_set plus @commit for
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* drivers still using legacy CRTC helpers, which is different from the
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* rules under atomic.
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*/
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void (*disable)(struct drm_crtc *crtc);
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/**
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* @enable:
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*
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* This callback should be used to enable the CRTC. With the atomic
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* drivers it is called before all encoders connected to this CRTC are
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* enabled through the encoder's own ->enable hook. If that sequence is
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* too simple drivers can just add their own hooks and call it from this
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* CRTC callback here by looping over all encoders connected to it using
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* for_each_encoder_on_crtc().
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*
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* This hook is used only by atomic helpers, for symmetry with @disable.
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* Atomic drivers don't need to implement it if there's no need to
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* enable anything at the CRTC level. To ensure that runtime PM handling
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* (using either DPMS or the new "ACTIVE" property) works
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* @enable must be the inverse of @disable for atomic drivers.
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*/
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void (*enable)(struct drm_crtc *crtc);
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/**
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@ -212,53 +390,228 @@ static inline void drm_crtc_helper_add(struct drm_crtc *crtc,
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/**
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* struct drm_encoder_helper_funcs - helper operations for encoders
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* @dpms: set power state
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* @mode_fixup: try to fixup proposed mode for this connector
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* @prepare: part of the disable sequence, called before the CRTC modeset
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* @commit: called after the CRTC modeset
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* @mode_set: set this mode, optional for atomic helpers
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* @get_crtc: return CRTC that the encoder is currently attached to
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* @detect: connection status detection
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* @disable: disable encoder when not in use (overrides DPMS off)
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* @enable: enable encoder
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* @atomic_check: check for validity of an atomic update
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*
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* The helper operations are called by the mid-layer CRTC helper.
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*
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* Note that with atomic helpers @dpms, @prepare and @commit hooks are
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* deprecated. Used @enable and @disable instead exclusively.
|
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*
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* With legacy crtc helpers there's a big semantic difference between @disable
|
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* and the other hooks: @disable also needs to release any resources acquired in
|
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* @mode_set (like shared PLLs).
|
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* These hooks are used by the legacy CRTC helpers, the transitional plane
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* helpers and the new atomic modesetting helpers.
|
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*/
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struct drm_encoder_helper_funcs {
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/**
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* @dpms:
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*
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* Callback to control power levels on the encoder. If the mode passed in
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* is unsupported, the provider must use the next lowest power level.
|
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* This is used by the legacy encoder helpers to implement DPMS
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* functionality in drm_helper_connector_dpms().
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*
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* This callback is also used to disable an encoder by calling it with
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* DRM_MODE_DPMS_OFF if the @disable hook isn't used.
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*
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* This callback is used by the legacy CRTC helpers. Atomic helpers
|
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* also support using this hook for enabling and disabling an encoder to
|
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* facilitate transitions to atomic, but it is deprecated. Instead
|
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* @enable and @disable should be used.
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*/
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void (*dpms)(struct drm_encoder *encoder, int mode);
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/**
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* @mode_fixup:
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*
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* This callback is used to validate and adjust a mode. The parameter
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* mode is the display mode that should be fed to the next element in
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* the display chain, either the final &drm_connector or a &drm_bridge.
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* The parameter adjusted_mode is the input mode the encoder requires. It
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* can be modified by this callback and does not need to match mode.
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*
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* This function is used by both legacy CRTC helpers and atomic helpers.
|
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* 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
|
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* allowed.
|
||||
*
|
||||
* Atomic drivers which need to inspect and adjust more state should
|
||||
* instead use the @atomic_check callback.
|
||||
*
|
||||
* RETURNS:
|
||||
*
|
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* True if an acceptable configuration is possible, false if the modeset
|
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* operation should be rejected.
|
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*/
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bool (*mode_fixup)(struct drm_encoder *encoder,
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const struct drm_display_mode *mode,
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struct drm_display_mode *adjusted_mode);
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/**
|
||||
* @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,
|
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struct drm_display_mode *mode,
|
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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
|
||||
*/
|
||||
|
|
|
|||
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