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>
diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
index fa56bb5..d99c452 100644
--- a/drivers/gpu/drm/drm_plane_helper.c
+++ b/drivers/gpu/drm/drm_plane_helper.c
@@ -27,7 +27,9 @@
#include <drm/drmP.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_rect.h>
+#include <drm/drm_atomic.h>
#include <drm/drm_crtc_helper.h>
+#include <drm/drm_atomic_helper.h>
#define SUBPIXEL_MASK 0xffff
@@ -464,7 +466,7 @@
if (plane->funcs->atomic_destroy_state)
plane->funcs->atomic_destroy_state(plane, plane_state);
else
- kfree(plane_state);
+ drm_atomic_helper_plane_destroy_state(plane, plane_state);
}
return ret;
@@ -505,15 +507,14 @@
if (plane->funcs->atomic_duplicate_state)
plane_state = plane->funcs->atomic_duplicate_state(plane);
else if (plane->state)
- plane_state = kmemdup(plane->state, sizeof(*plane_state),
- GFP_KERNEL);
+ plane_state = drm_atomic_helper_plane_duplicate_state(plane);
else
plane_state = kzalloc(sizeof(*plane_state), GFP_KERNEL);
if (!plane_state)
return -ENOMEM;
plane_state->crtc = crtc;
- plane_state->fb = fb;
+ drm_atomic_set_fb_for_plane(plane_state, fb);
plane_state->crtc_x = crtc_x;
plane_state->crtc_y = crtc_y;
plane_state->crtc_h = crtc_h;
@@ -552,15 +553,14 @@
if (plane->funcs->atomic_duplicate_state)
plane_state = plane->funcs->atomic_duplicate_state(plane);
else if (plane->state)
- plane_state = kmemdup(plane->state, sizeof(*plane_state),
- GFP_KERNEL);
+ plane_state = drm_atomic_helper_plane_duplicate_state(plane);
else
plane_state = kzalloc(sizeof(*plane_state), GFP_KERNEL);
if (!plane_state)
return -ENOMEM;
plane_state->crtc = NULL;
- plane_state->fb = NULL;
+ drm_atomic_set_fb_for_plane(plane_state, NULL);
return drm_plane_helper_commit(plane, plane_state, plane->fb);
}