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drm: Initialize struct drm_crtc_state.no_vblank from device settings

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At the end of a commit, atomic helpers can generate a fake VBLANK event
automatically. Originally implemented for writeback connectors, the
functionality can be used by any driver and/or hardware without proper
VBLANK interrupt.

The patch updates the documentation to make this behaviour official:
settings struct drm_crtc_state.no_vblank to true enables automatic
generation of fake VBLANK events.

The new interface drm_dev_has_vblank() returns true if vblanking has
been initialized for a device, or false otherwise. Atomic helpers use
this function when initializing no_vblank in the CRTC state in
drm_atomic_helper_check_modeset(). If vblanking has been initialized
for a device, no_blank is disabled. Otherwise it's enabled. Hence,
atomic helpers will automatically send out fake VBLANK events with any
driver that did not initialize vblanking.

v5:
	* more precise documentation and commit message
v4:
	* replace drm_crtc_has_vblank() with drm_dev_has_vblank()
	* add drm_dev_has_vblank() in this patch
	* move driver changes into separate patches
v3:
	* squash all related changes patches into this patch

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200129120531.6891-2-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann
2020-01-29 13:05:17 +01:00
parent 86a9360be1
commit 7beb691f1e
5 changed files with 70 additions and 10 deletions
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10
drivers/gpu/drm/drm_atomic_helper.c
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@@ -583,6 +583,7 @@ mode_valid(struct drm_atomic_state *state)
* &drm_crtc_state.connectors_changed is set when a connector is added or
* removed from the CRTC. &drm_crtc_state.active_changed is set when
* &drm_crtc_state.active changes, which is used for DPMS.
* &drm_crtc_state.no_vblank is set from the result of drm_dev_has_vblank().
* See also: drm_atomic_crtc_needs_modeset()
*
* IMPORTANT:
@@ -649,6 +650,11 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
return -EINVAL;
}
if (drm_dev_has_vblank(dev))
new_crtc_state->no_vblank = false;
else
new_crtc_state->no_vblank = true;
}
ret = handle_conflicting_encoders(state, false);
@@ -2215,7 +2221,9 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies);
* when a job is queued, and any change to the pipeline that does not touch the
* connector is leading to timeouts when calling
* drm_atomic_helper_wait_for_vblanks() or
* drm_atomic_helper_wait_for_flip_done().
* drm_atomic_helper_wait_for_flip_done(). In addition to writeback
* connectors, this function can also fake VBLANK events for CRTCs without
* VBLANK interrupt.
*
* This is part of the atomic helper support for nonblocking commits, see
* drm_atomic_helper_setup_commit() for an overview.