diff options
Diffstat (limited to 'include/drm/drm_crtc.h')
| -rw-r--r-- | include/drm/drm_crtc.h | 56 |
1 files changed, 43 insertions, 13 deletions
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index a544b7502493..61932f55f788 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -109,8 +109,6 @@ struct drm_plane_helper_funcs; * @ctm: Transformation matrix * @gamma_lut: Lookup table for converting pixel data after the * conversion matrix - * @event: optional pointer to a DRM event to signal upon completion of the - * state update * @state: backpointer to global drm_atomic_state * * Note that the distinction between @enable and @active is rather subtile: @@ -159,6 +157,46 @@ struct drm_crtc_state { struct drm_property_blob *ctm; struct drm_property_blob *gamma_lut; + /** + * @event: + * + * Optional pointer to a DRM event to signal upon completion of the + * state update. The driver must send out the event when the atomic + * commit operation completes. There are two cases: + * + * - The event is for a CRTC which is being disabled through this + * atomic commit. In that case the event can be send out any time + * after the hardware has stopped scanning out the current + * framebuffers. It should contain the timestamp and counter for the + * last vblank before the display pipeline was shut off. + * + * - For a CRTC which is enabled at the end of the commit (even when it + * undergoes an full modeset) the vblank timestamp and counter must + * be for the vblank right before the first frame that scans out the + * new set of buffers. Again the event can only be sent out after the + * hardware has stopped scanning out the old buffers. + * + * - Events for disabled CRTCs are not allowed, and drivers can ignore + * that 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 atomic commit. 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. + * + * For hardware which supports some means to synchronize vblank + * interrupt delivery with committing display state there's also + * drm_crtc_arm_vblank_event(). See the documentation of that function + * for a detailed discussion of the constraints it needs to be used + * safely. + */ struct drm_pending_vblank_event *event; struct drm_atomic_state *state; @@ -835,17 +873,9 @@ struct drm_mode_config_funcs { * CRTC index supplied in &drm_event to userspace. * * The drm core will supply a struct &drm_event in the event - * member of each CRTC's &drm_crtc_state structure. 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 atomic commit. 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. + * member of each CRTC's &drm_crtc_state structure. See the + * documentation for &drm_crtc_state for more details about the precise + * semantics of this event. * * NOTE: * |