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author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-11-04 21:57:27 (GMT) |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-11-06 20:08:37 (GMT) |
commit | 321ebf04dc7ab5c54d658f93db0ffe35277664ab (patch) | |
tree | 91fcbe2b49f701015e1fbbc8fb98800b1a297fa1 /drivers/gpu/drm/drm_atomic.c | |
parent | 3150c7d0c686ffee9e414ccce705c34ebcbf4e30 (diff) | |
download | linux-321ebf04dc7ab5c54d658f93db0ffe35277664ab.tar.xz |
drm/atomic: Refcounting for plane_state->fb
So my original plan was that the drm core refcounts framebuffers like
with the legacy ioctls. But that doesn't work for a bunch of reasons:
- State objects might live longer than until the next fb change
happens for a plane. For example delayed cleanup work only happens
_after_ the pageflip ioctl has completed. So this definitely doesn't
work without the plane state holding its own references.
- The other issue is transition from legacy to atomic implementations,
where the driver works under a mix of both worlds. Which means
legacy paths might not properly update the ->fb pointer under
plane->state->fb. Which is a bit a problem when then someone comes
around and _does_ try to clean it up when it's long gone.
The second issue is just a bit a transition bug, since drivers should
update plane->state->fb in all the paths that aren't converted yet.
But a bit more robustness for the transition can't hurt - we pull
similar tricks with cleaning up the old fb in the transitional helpers
already.
The pattern for drivers that transition is
if (plane->state)
drm_atomic_set_fb_for_plane(plane->state, plane->fb);
inserted after the fb update has logically completed at the end of
->set_config (or ->set_base/mode_set if using the crtc helpers),
->page_flip, ->update_plane or any other entry point which updates
plane->fb.
v2: Update kerneldoc - copypasta fail.
v3: Fix spelling in the commit message (Sean).
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Diffstat (limited to 'drivers/gpu/drm/drm_atomic.c')
-rw-r--r-- | drivers/gpu/drm/drm_atomic.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index ad15a88..ed991ba 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -368,6 +368,34 @@ drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state, EXPORT_SYMBOL(drm_atomic_set_crtc_for_plane); /** + * drm_atomic_set_fb_for_plane - set crtc for plane + * @plane_state: atomic state object for the plane + * @fb: fb to use for the plane + * + * Changing the assigned framebuffer for a plane requires us to grab a reference + * to the new fb and drop the reference to the old fb, if there is one. This + * function takes care of all these details besides updating the pointer in the + * state object itself. + */ +void +drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state, + struct drm_framebuffer *fb) +{ + if (plane_state->fb) + drm_framebuffer_unreference(plane_state->fb); + if (fb) + drm_framebuffer_reference(fb); + plane_state->fb = fb; + + if (fb) + DRM_DEBUG_KMS("Set [FB:%d] for plane state %p\n", + fb->base.id, plane_state); + else + DRM_DEBUG_KMS("Set [NOFB] for plane state %p\n", plane_state); +} +EXPORT_SYMBOL(drm_atomic_set_fb_for_plane); + +/** * drm_atomic_set_crtc_for_connector - set crtc for connector * @conn_state: atomic state object for the connector * @crtc: crtc to use for the connector |